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T. V. Rajanbabu - One of the best experts on this subject based on the ideXlab platform.
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Broadly Applicable Stereoselective Syntheses of Serrulatane, Amphilectane Diterpenes, and Their Diastereoisomeric Congeners Using Asymmetric Hydrovinylation for Absolute Stereochemical Control.
Journal of the American Chemical Society, 2018Co-Authors: Srinivasarao Tenneti, Hwan Jung Lim, Souvagya Biswas, Glen Adam Cox, Daniel J. Mans, T. V. RajanbabuAbstract:A stereogenic center, placed at an exocyclic location next to a chiral carbon in a ring to which it is attached, is a ubiquitous structural motif seen in many bioactive natural products, including di- and triterpenes and steroids. Installation of these centers has been a long-standing problem in organic chemistry. Few classes of compounds illustrate this problem better than serrulatanes and amphilectanes, which carry multiple methyl-bearing exocyclic chiral centers. Nickel-catalyzed asymmetric Hydrovinylation (AHV) of vinylarenes and 1,3-dienes such as 1-vinylcycloalkenes provides an exceptionally facile way of introducing these chiral centers. This Article documents our efforts to demonstrate the generality of AHV to access not only the natural products but also their various diastereoisomeric derivatives. Key to success here is the availability of highly tunable phosphoramidite Ni(II) complexes useful for overcoming the inherent selectivity of the chiral intermediates. The yields for Hydrovinylation (HV...
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Asymmetric Hydrovinylation of 1-Vinylcycloalkenes. Reagent Control of Regio- and Stereoselectivity
2016Co-Authors: T. V. RajanbabuAbstract:ABSTRACT: 1-Vinylcycloalkenes undergo highly regio-and enantioselective (>98 % ee) 1,4-Hydrovinylation (HV) when treated with ethylene (1 atm) at room temperature in the presence of [(S,S)-2,4-bis-diphenylphosphinopen-tane (BDPP)]CoCl2 (0.05 equiv) and methylaluminoxane. The minor 1,2-HV products, seen only in 1-vinyl-cyclohexene (∼15%) and 1-vinylcycloheptene (2%), are formed as racemic mixtures. The corresponding Ni(II)-catalyzed HV reactions of these substrates give mostly the 1,2-adducts. Racemic 4-tert-butyl-1-vinylcyclohexene, when treated with Co[(S,S)-(BDPP)]Cl2 and ethylene, under-goes a rare enantiodivergent reaction giving two diastereomers each in>98 % ee. Nickel(II)-catalyzed asymmetric Hydrovinylation (HV) of1-vinylcycloalkenes is a powerful reaction that has been used to install exocyclic methyl-bearing chiral centers wit
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Chemoselective Reactions of (E)‑1,3-Dienes: Cobalt-Mediated Isomerization to (Z)‑1,3-Dienes and Reactions with Ethylene
2016Co-Authors: Yam N. Timsina, Souvagya Biswas, T. V. RajanbabuAbstract:ABSTRACT: In the asymmetric Hydrovinylation (HV) of an E/Z-mixture of a prototypical 1,3-diene with (S,S)-(DIOP)CoCl2 or (S,S)-(BDPP)CoCl2 catalyst in the presence of Me3Al, the (E)-isomer reacts significantly faster, leaving behind the Z-isomer intact at the end of the reaction. The presumed [LCo−H]+-intermediate, espe-cially when L is a large-bite angle ligand, similar to DIOP and BDPP, promote an unusual isomerization of (E/Z)-mixtures of 1,3-dienes to isomerically pure Z-isomers. A mechanism that involves an intramolecular hydride addition via an [η4-(diene)(LCo−H)]+ complex, followed by π−σ−π isomerization of the intermediate Co(allyl) species, is proposed for this reaction. We recently reported a new protocol for a highly enantio-selective Co(II)-catalyzed asymmetric Hydrovinylation (HV) of unactivated 1,3-dienes that involves the use of
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cobalt catalysed asymmetric Hydrovinylation of 1 3 dienes
Chemical Science, 2015Co-Authors: Yam N. Timsina, Rakesh Sharma, T. V. RajanbabuAbstract:In the presence of bidentate 1,n-bis-diphenylphosphinoalkane-CoCl2 complexes {Cl2Co[P ∼ P]} and Me3Al or methylaluminoxane, acyclic (E)-1,3-dienes react with ethylene (1 atmosphere) to give excellent yields of Hydrovinylation products. The regioselectivity (1,4- or 1,2-addition) and the alkene configuration (E- or Z-) of the resulting product depend on the nature of the ligand and temperature at which the reaction is carried out. Cobalt(II)-complexes of 1,1-diphenylphosphinomethane and similar ligands with narrow bite angles give mostly 1,2-addition, retaining the E-geometry of the original diene. Complexes of most other ligands at low temperature (−40 °C) give almost exclusively a single branched product, (Z)-3-alkylhexa-1,4-diene, which arises from a 1,4-Hydrovinylation reaction. A minor product is the linear adduct, a 6-alkyl-hexa-1,4-diene, also arising from a 1,4-addition of ethylene. As the temperature is increased, a higher proportion of the major branched-1,4-adduct appears as the (E)-isomer. The unexpectedly high selectivity seen in the Co-catalysed reaction as compared to the corresponding Ni-catalysed reaction can be rationalized by invoking the intermediacy of an η4-[(diene)[P ∼ P]CoH]+-complex and its subsequent reactions. The enhanced reactivity of terminal E-1,3-dienes over the corresponding Z-dienes can also be explained on the basis of the ease of formation of this η4-complex in the former case. The lack of reactivity of the X2Co(dppb) (X = Cl, Br) complexes in the presence of Zn/ZnI2 makes the Me3Al-mediated reaction different from the previously reported hydroalkenylation of dienes. Electron-rich phospholanes, bis-oxazolines and N-heterocyclic carbenes appear to be poor ligands for the Co(II)-catalysed Hydrovinylation of 1,3-dienes. An extensive survey of chiral ligands reveals that complexes of DIOP, BDPP and Josiphos ligands are quite effective for these reactions even at −45 °C and enantioselectivities in the range of 90–99% ee can be realized for a variety of 1,3-dienes. Cobalt(II)-complex of an electron-deficient Josiphos ligand is especially active, requiring only <1 mol% catalyst to effect the reactions.
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Cobalt-catalysed asymmetric Hydrovinylation of 1,3-dienes
Chemical science, 2015Co-Authors: Yam N. Timsina, Rakesh Sharma, T. V. RajanbabuAbstract:In the presence of bidentate 1,n-bis-diphenylphosphinoalkane-CoCl2 complexes {Cl2Co[P ∼ P]} and Me3Al or methylaluminoxane, acyclic (E)-1,3-dienes react with ethylene (1 atmosphere) to give excellent yields of Hydrovinylation products. The regioselectivity (1,4- or 1,2-addition) and the alkene configuration (E- or Z-) of the resulting product depend on the nature of the ligand and temperature at which the reaction is carried out. Cobalt(II)-complexes of 1,1-diphenylphosphinomethane and similar ligands with narrow bite angles give mostly 1,2-addition, retaining the E-geometry of the original diene. Complexes of most other ligands at low temperature (−40 °C) give almost exclusively a single branched product, (Z)-3-alkylhexa-1,4-diene, which arises from a 1,4-Hydrovinylation reaction. A minor product is the linear adduct, a 6-alkyl-hexa-1,4-diene, also arising from a 1,4-addition of ethylene. As the temperature is increased, a higher proportion of the major branched-1,4-adduct appears as the (E)-isomer. The unexpectedly high selectivity seen in the Co-catalysed reaction as compared to the corresponding Ni-catalysed reaction can be rationalized by invoking the intermediacy of an η4-[(diene)[P ∼ P]CoH]+-complex and its subsequent reactions. The enhanced reactivity of terminal E-1,3-dienes over the corresponding Z-dienes can also be explained on the basis of the ease of formation of this η4-complex in the former case. The lack of reactivity of the X2Co(dppb) (X = Cl, Br) complexes in the presence of Zn/ZnI2 makes the Me3Al-mediated reaction different from the previously reported hydroalkenylation of dienes. Electron-rich phospholanes, bis-oxazolines and N-heterocyclic carbenes appear to be poor ligands for the Co(II)-catalysed Hydrovinylation of 1,3-dienes. An extensive survey of chiral ligands reveals that complexes of DIOP, BDPP and Josiphos ligands are quite effective for these reactions even at −45 °C and enantioselectivities in the range of 90–99% ee can be realized for a variety of 1,3-dienes. Cobalt(II)-complex of an electron-deficient Josiphos ligand is especially active, requiring only
Paola Pace - One of the best experts on this subject based on the ideXlab platform.
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the palladium catalyzed hydroarylation and Hydrovinylation of tertiary 3 o acetoxyaryl and 3 o benzoyloxyaryl propynols a route to 4 aryl and 4 vinyl 2 2 dimethyl 3 chromenes
European Journal of Organic Chemistry, 2000Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The palladium-catalyzed hydroarylation and Hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and Hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.
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The Palladium‐Catalyzed Hydroarylation and Hydrovinylation of Tertiary 3‐(o‐Acetoxyaryl)‐ and 3‐(o‐Benzoyloxyaryl)propynols − A Route to 4‐Aryl‐ and 4‐Vinyl‐2,2‐Dimethyl‐3‐chromenes
European Journal of Organic Chemistry, 2000Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The palladium-catalyzed hydroarylation and Hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and Hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.
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palladium catalyzed Hydrovinylation of vinyl triflates with alkynes an approach to the synthesis of 3 vinylfuran 2 5h ones
European Journal of Organic Chemistry, 1999Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The reaction of alkynes with vinyl triflates in the presence of catalytic amounts of Pd(OAc)2 and HCOOK, omitting phosphane ligands, affords Hydrovinylation products usually in good to high yields. The reaction has been employed to develop a regioselective synthesis of 3-vinylfuran-2(5H)-ones from methyl 4-hydroxy-2-butynoates.
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Palladium‐Catalyzed Hydrovinylation of Vinyl Triflates with Alkynes An Approach to the Synthesis of 3‐Vinylfuran‐2(5H)‐ones
European Journal of Organic Chemistry, 1999Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The reaction of alkynes with vinyl triflates in the presence of catalytic amounts of Pd(OAc)2 and HCOOK, omitting phosphane ligands, affords Hydrovinylation products usually in good to high yields. The reaction has been employed to develop a regioselective synthesis of 3-vinylfuran-2(5H)-ones from methyl 4-hydroxy-2-butynoates.
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Palladium-catalysed hydroarylation and Hydrovinylation of 3,3-dialkoxy-1-aryl-1-propynes. An approach to 3-aryl- and 3-vinylquinolines
Tetrahedron, 1996Co-Authors: Sandro Cacchi, Fabio Marinelli, Giancarlo Fabrizi, Leonardo Moro, Paola PaceAbstract:Abstract Acetylenic acetals and ketals have been reacted with aryl and vinyl halides to generate hydroarylation and Hydrovinylation products. The reaction proceeds with high regioselectivity. The carbopalladation step appears to be mainly controlled by steric effects and the new carbon-carbon bond is generated preferentially on the carbon bearing the acetal group. The reaction has been employed to develop a regioselective synthesis of 3-aryl and 3-vinylquinolines.
Gerhard Hilt - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Non-Conjugated Trienes via In Situ Hydrovinylation/Wittig Olefination of Unsaturated Phosphonium Salts
Synthesis, 2017Co-Authors: Monika Ballmann, Felicia Weber, Lars Erik Sattler, Gerhard HiltAbstract:A cobalt-catalysed 1,4-Hydrovinylation reaction is successfully applied in a sequential three-component transformation of unsaturated phosphonium bromides, 1,3-dienes, and aldehydes leading to non-conjugated products with a 1,4-diene subunit in good to excellent yields. The Hydrovinylation provides regioselectively diene structures with one exo double bond whereas the third double bond can be introduced via an in situ Wittig or Horner–Wadsworth–Emmons olefination leading to 1,4,7-trienes suitable for further double bond functionalisations.
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Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes
Beilstein journal of organic chemistry, 2015Co-Authors: Philipp Röse, Steffen P. Emge, Jun-ichi Yoshida, Gerhard HiltAbstract:The cobalt(I)-catalysed 1,4-Hydrovinylation reaction of allyloxytrimethylsilane and allyl alcohol with substituted 1,3-dienes leads to hydroxy-functionalised 1,4-dienes in excellent regio- and diastereoselective fashion. Those 1,4-dienols can be converted into tetrahydrofuran and pyran derivatives under indirect electrochemical conditions generating selenium or iodonium cations. The reactions proceed in good yields and regioselectivities for the formation of single diastereomers.
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Synthesis of Tri‑, Tetra‑, and Pentacarbonyl Derivatives via Ozonolysis of 1,4-Dienes and Cyclization to Polyaromatic Systems
2014Co-Authors: Laura Kersten, Klaus Harms, Gerhard HiltAbstract:The aim of this work was the synthesis of polyaromatic systems by cyclization of β-polycarbonyls. Useful synthons for β-polycarbonyl derivatives are branched 1,4-dienes generated by cobalt-catalyzed Hydrovinylation of terminal alkenes and 2,3-dimethyl-1,3-butadiene. Thus, a series of tri-, tetra-, and pentacarbonyl synthons was successfully synthesized. Subsequently, these synthons were examined in an ozonolysis/cyclization reaction sequence. Polyaromatic derivatives were obtained in good yields and the method was applied in the synthesis of the natural product Kwanzoquinone A
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Scope and limitations of 1,3,5-hexatriene derivatives in regioselective cobalt-catalyzed reactions.
Organic letters, 2013Co-Authors: Anastasia Schmidt, Gerhard HiltAbstract:Applications of 1,3,5-hexatriene derivatives in atom-economic cobalt-catalyzed transformations, such as the Diels–Alder reaction with alkynes, the 1,4-Hydrovinylation reaction with terminal alkenes, and the 1,4-hydrohexatrienylation reaction, are investigated. In all cases, regioselective transformations were found to generate cyclic derivatives such as stilbenes or acyclic products with a high control of the double bond geometry in the skipped trienes derived from the 1,4-Hydrovinylation process or the tetraenes generated in the so far unprecedented 1,4-hydrohexatrienylation reaction.
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Hydrovinylation reactions atom economic transformations with steadily increasing synthetic potential
European Journal of Organic Chemistry, 2012Co-Authors: Gerhard HiltAbstract:The intermolecular carbon–carbon bond formation between two alkenes also known as 1,2-Hydrovinylation reaction can be realised with different transition metal catalysts. The application of styrene derivatives, norbornenes and other alkenes in asymmetric catalysis with a variety of chiral ligands leads to α-chiral alkene products in an atom-economic transformation. Accordingly, the 1,2-Hydrovinylation is one of just a few asymmetric transformations which produce stereogenic centres in the absence of polarised functional groups. The 1,4-Hydrovinylation of terminal alkenes and 1,3-dienes can be controlled by the electronic nature of the alkene starting material for the selective formation of linear or branched 1,4-dienes. These adducts can be used for the synthesis of 1,3- as well as 1,4-dicarbonyl derivatives upon ozonolysis of suitable intermediates. As an extension of the 1,4-Hydrovinylation reaction a cobalt-catalysed 1,4-hydrobutadienylation reaction is reported where two different 1,3-dienes react selectively for the formation of 1,3,6-trienes.
Antonio Arcadi - One of the best experts on this subject based on the ideXlab platform.
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Rh-Catalyzed Sequential Hydroarylation/Hydrovinylation-Heterocyclization of β-(2-Aminophenyl)-α,β-ynones with Organoboron Derivatives: A New Approach to Functionalized Quinolines
Synlett, 2006Co-Authors: Giorgio Abbiati, Antonio Arcadi, Fabio Marinelli, Elisabetta Rossi, Mirella VerdecchiaAbstract:4-Aryl and 4-vinyl quinolines were prepared via a sequential procedure involving regioselective Rh(acac)(C 2 H 2 )/dppf-catalyzed hydroarylation/Hydrovinylation of β-(2-aminophenyl)-α,β-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbonyl.
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rh catalyzed sequential hydroarylation Hydrovinylation heterocyclization of β 2 aminophenyl α β ynones with organoboron derivatives a new approach to functionalized quinolines
Synlett, 2006Co-Authors: Giorgio Abbiati, Antonio Arcadi, Fabio Marinelli, Elisabetta Rossi, Mirella VerdecchiaAbstract:4-Aryl and 4-vinyl quinolines were prepared via a sequential procedure involving regioselective Rh(acac)(C 2 H 2 )/dppf-catalyzed hydroarylation/Hydrovinylation of β-(2-aminophenyl)-α,β-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbonyl.
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the palladium catalyzed hydroarylation and Hydrovinylation of tertiary 3 o acetoxyaryl and 3 o benzoyloxyaryl propynols a route to 4 aryl and 4 vinyl 2 2 dimethyl 3 chromenes
European Journal of Organic Chemistry, 2000Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The palladium-catalyzed hydroarylation and Hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and Hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.
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The Palladium‐Catalyzed Hydroarylation and Hydrovinylation of Tertiary 3‐(o‐Acetoxyaryl)‐ and 3‐(o‐Benzoyloxyaryl)propynols − A Route to 4‐Aryl‐ and 4‐Vinyl‐2,2‐Dimethyl‐3‐chromenes
European Journal of Organic Chemistry, 2000Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The palladium-catalyzed hydroarylation and Hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and Hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.
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palladium catalyzed Hydrovinylation of vinyl triflates with alkynes an approach to the synthesis of 3 vinylfuran 2 5h ones
European Journal of Organic Chemistry, 1999Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The reaction of alkynes with vinyl triflates in the presence of catalytic amounts of Pd(OAc)2 and HCOOK, omitting phosphane ligands, affords Hydrovinylation products usually in good to high yields. The reaction has been employed to develop a regioselective synthesis of 3-vinylfuran-2(5H)-ones from methyl 4-hydroxy-2-butynoates.
Fabio Marinelli - One of the best experts on this subject based on the ideXlab platform.
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Rh-Catalyzed Sequential Hydroarylation/Hydrovinylation-Heterocyclization of β-(2-Aminophenyl)-α,β-ynones with Organoboron Derivatives: A New Approach to Functionalized Quinolines
Synlett, 2006Co-Authors: Giorgio Abbiati, Antonio Arcadi, Fabio Marinelli, Elisabetta Rossi, Mirella VerdecchiaAbstract:4-Aryl and 4-vinyl quinolines were prepared via a sequential procedure involving regioselective Rh(acac)(C 2 H 2 )/dppf-catalyzed hydroarylation/Hydrovinylation of β-(2-aminophenyl)-α,β-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbonyl.
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rh catalyzed sequential hydroarylation Hydrovinylation heterocyclization of β 2 aminophenyl α β ynones with organoboron derivatives a new approach to functionalized quinolines
Synlett, 2006Co-Authors: Giorgio Abbiati, Antonio Arcadi, Fabio Marinelli, Elisabetta Rossi, Mirella VerdecchiaAbstract:4-Aryl and 4-vinyl quinolines were prepared via a sequential procedure involving regioselective Rh(acac)(C 2 H 2 )/dppf-catalyzed hydroarylation/Hydrovinylation of β-(2-aminophenyl)-α,β-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbonyl.
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Rh-catalyzed sequential hydroarylation/Hydrovinylation-heterocyclization of beta-(2-aminophenyl)-alpha,beta-ynones with organoboron derivatives : a new approach to functionalized quinolines
'Georg Thieme Verlag KG', 2006Co-Authors: Giorgio Abbiati, Fabio Marinelli, A. Arcadi, E. Rossi, Mirella VerdecchiaAbstract:4-Aryl and 4-vinyl quinolines were prepared via a sequential procedure involving regioselective Rh(acac)(C2H2)/dppf catalyzed hydroarylation/Hydrovinylation of beta-(2-aminophenyl)- alfa,beta-ynones with arylboronic acids or potassium aryl and vinyl trifluoroborates, followed by nucleophilic attack of the amino group onto the carbony
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the palladium catalyzed hydroarylation and Hydrovinylation of tertiary 3 o acetoxyaryl and 3 o benzoyloxyaryl propynols a route to 4 aryl and 4 vinyl 2 2 dimethyl 3 chromenes
European Journal of Organic Chemistry, 2000Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The palladium-catalyzed hydroarylation and Hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and Hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.
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The Palladium‐Catalyzed Hydroarylation and Hydrovinylation of Tertiary 3‐(o‐Acetoxyaryl)‐ and 3‐(o‐Benzoyloxyaryl)propynols − A Route to 4‐Aryl‐ and 4‐Vinyl‐2,2‐Dimethyl‐3‐chromenes
European Journal of Organic Chemistry, 2000Co-Authors: Antonio Arcadi, Fabio Marinelli, Sandro Cacchi, Giancarlo Fabrizi, Paola PaceAbstract:The palladium-catalyzed hydroarylation and Hydrovinylation of tertiary 3-(o-acetoxyaryl)- and 3-(o-benzoyloxyaryl)propynols provides a regio- and stereoselective route to allylic alcohols with aryl and vinyl substituents which can be readily converted into the corresponding chromene derivatives. The hydroarylation and Hydrovinylation reaction is believed to proceed through a carbopalladation step whose regiochemistry is primarily controlled by the directing effect of the tertiary hydroxy group.
