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Fumie Sato - One of the best experts on this subject based on the ideXlab platform.
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synthesis of optically active 5 tert butyldimethylsiloxy 2 cyclohexenone and its 6 substituted derivatives as useful chiral building blocks for the synthesis of cyclohexane rings syntheses of carvone penienone and penihydrone
Journal of the American Chemical Society, 1999Co-Authors: Georges P.‐j. Hareau, Shinichi Hikichi, Masakazu Koiwa, Fumie SatoAbstract:Optically active 5-(tert-butyldimethylsiloxy)-2-cyclohexenone (1) and its 6-substituted derivatives 2a,b were synthesized from the readily available optically active ethyl 3-(tert-butyldimethylsiloxy)-5-hexenoate (4), where the Ti(II)-mediated intramolecular Nucleophilic Acyl Substitution reaction and the FeCl3-mediated ring expansion reaction of a 1-hydroxybicyclo[3.1.0]hexane are the key reactions. The enone 1 reacted with higher-order cyanocuprates with excellent diastereoselectivity to afford the trans-addition products, trans-13, in excellent yields. The reaction of 1 with lower-order cyanocuprates proceeded with moderate to excellent syn-selectivity to afford cis-13. Treatment of trans- and cis-13 with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or catalyst p-TSA (p-toluenesulfonic acid) resulted in a β-elimination reaction to furnish the corresponding optically active 5-substituted-2-cyclohexenones 14. The 1,4-addition reaction of 2a and 2b with organocyanocuprates followed by treatment of the resulti...
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Practical synthesis of optically active bicyclic oxazolidinylpiperidines, chiral building blocks for preparing 1-deoxyazasugars, from serine
Tetrahedron Letters, 1999Co-Authors: Masaaki Shirai, Sentaro Okamoto, Fumie SatoAbstract:Abstract Optically active bicyclic oxazolidinylpiperidines 1a , 1b , 1c and 1d , known chiral building blocks for preparing 1-deoxyazasugars, were synthesized in high overall yield from D-serine by a method wherein the titanium(II)-mediated intramolecular Nucleophilic Acyl Substitution and FeCl 3 -mediated ring enlargement of bicyclic cyclopropanols are the key reactions.
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Synthesis of optically active 6-amino-2-cycloheptenone as a convenient chiral building block for the preparation of 6-alkyl-2-cycloheptenone
Tetrahedron Letters, 1999Co-Authors: Masakazu Koiwa, Georges P.‐j. Hareau, Daisuke Morizono, Fumie SatoAbstract:Abstract Optically active 6-amino-2-cycloheptenone 5 has been prepared from ethyl 2(E),6-heptadienoate where the Michael addition of a chiral amine, Ti(II)-mediated intramolecular Nucleophilic Acyl Substitution reaction and FeCl3-mediated ring expansion are the key steps. The compound 5 undergoes highly diastereoselective conjugate addition of a Grignard reagent in the presence of a catalytic amount of Li2Cu(CN)Cl2 to provide the corresponding cis-adducts which, in turn, are converted in to 6-alkyl substituted 2-cycloheptenones by treatment with p-TSA.
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Efficient and practical method for synthesizing optically active γ-trityloxymethyl-α-alkylidene-γ-butyrolactones using Ti(II)-mediated intramolecular Nucleophilic Acyl Substitution reaction
Tetrahedron Letters, 1998Co-Authors: Z. P. Mincheva, Yuan Gao, Fumie SatoAbstract:Abstract An efficient and highly stereoselective method for synthesizing optically active γ-trityloxymethyl-α-alkylidene-γ-butyrolactones having a stereodefined mono or disubstituted exocyclic double bond, starting from commercially available non-racemic glycidyl tritylether has been developed in which a titanium(II)-mediated intramolecular Nucleophilic Acyl Substitution reaction is a key reaction.
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efficient and practical synthesis of optically active 5 t butyldimethylsiloxy 2 cyclohexenone as a convenient chiral 2 5 cyclohexadienone synthon
Tetrahedron Letters, 1997Co-Authors: Shinichi Hikichi, Georges P.‐j. Hareau, Fumie SatoAbstract:An efficient and practical method for the preparation of optically active 5-t-butyldimethylsiloxy-2-cyclohexenone (3), a convenient chiral 2,5-cyclohexadienone synthon, from readily available ethyl 4-chloro-3-hydroxy-butyrate (7) has been developed where Ti(II)-mediated intramolecular Nucleophilic Acyl Substitution and FeCl3-mediated ring expansion are the key reactions. The synthesis of racemic 6-t-butyldimethylsiloxy-2-cycloheptenone (10), a potential 2,6-cycloheptadienone synthon, is also described.
Gary A. Molander - One of the best experts on this subject based on the ideXlab platform.
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Sequenced reactions with samarium(II) iodide. Sequential intramolecular Reformatsky/Nucleophilic Acyl Substitution reactions for the synthesis of medium-sized carbocycles.
The Journal of organic chemistry, 2002Co-Authors: Gary A. Molander, Giles A. Brown, Isabel GràciaAbstract:Samarium(II) iodide was used to access eight- and nine-membered carbocycles via a domino reaction comprised of a Reformatsky reaction followed by a Nucleophilic Acyl Substitution reaction. This method represents a general and efficient approach to a variety of highly functionalized, stereodefined carbocycles.
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sequenced reactions with samarium ii iodide sequential intramolecular reformatsky Nucleophilic Acyl Substitution reactions for the synthesis of medium sized carbocycles
Journal of Organic Chemistry, 2002Co-Authors: Gary A. Molander, Giles A. Brown, Isabel GràciaAbstract:Samarium(II) iodide was used to access eight- and nine-membered carbocycles via a domino reaction comprised of a Reformatsky reaction followed by a Nucleophilic Acyl Substitution reaction. This method represents a general and efficient approach to a variety of highly functionalized, stereodefined carbocycles.
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SEQUENCED REACTIONS WITH SAMARIUM(II) IODIDE. A COMPLEMENTARY ANNULATION PROCESS PROVIDING ACCESS TO SEVEN-, EIGHT-, AND NINE-MEMBERED CARBOCYCLES
The Journal of Organic Chemistry, 1999Co-Authors: Gary A. Molander, Fouzia MachrouhiAbstract:Samarium(II) iodide promotes an efficient one-pot annulation reaction between ω-iodo esters and 2-(ω-chloroalkyl)cycloalkanones. An initial intermolecular carbonyl addition reaction between the iodo ester and the ketone generates a lactone intermediate. The lactone undergoes a subsequent Nucleophilic Acyl Substitution reaction with an organosamarium derived from the chloride. Nickel(II) iodide is an efficient catalyst for the first step of the process, and light is utilized to promote the second step. Seven-, eight-, and nine-membered rings can be accessed by this sequential dianionic process. This annulative approach to carbocycles is complementary to previously reported procedures.
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sequenced reactions with samarium ii iodide intermolecular ketyl olefin coupling intramolecular Nucleophilic Acyl Substitution for the preparation of six seven and eight membered carbocycles
Tetrahedron, 1998Co-Authors: Gary A. Molander, Masakazu SonoAbstract:Abstract A samarium(II) iodide-promoted sequence consisting of an intermolecular ketyl-olefin coupling followed by an intramolecular Nucleophilic Acyl Substitution is described. This process leads to functionalized six- to eight-membered monocyclic and bicyclic ring systems in moderate to good yields.
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sequential Nucleophilic Acyl Substitution alkenyl transfer reactions mediated by samarium ii iodide
Journal of Organic Chemistry, 1998Co-Authors: Gary A. Molander, Christina R. HarrisAbstract:Samarium(II) iodide (SmI2) has been employed in a one-pot, three-step, Nucleophilic Acyl Substitution/ketyl−olefin coupling/β-elimination reaction sequence. This novel protocol combines two recently developed SmI2-mediated processes to permit the net delivery of an alkenyl moiety to a ketone carbonyl generated as an intermediate along the sequential reaction pathway. A remarkable measure of stereocontrol over three to five contiguous stereocenters is established in the process as a result of the excellent facial selectivity conveyed in the ketyl−olefin coupling reaction. Unique to the SmI2-mediated process, the relative asymmetric induction engendered in these addition reactions is complementary to more traditional Nucleophilic addition reactions in that the alkenyl group is delivered to the carbonyl center by an attached tether. Moreover, the protocol avoids the basic reaction conditions characteristic of alkenylmagnesium halides and alkenyllithium reagents.
Christina R. Harris - One of the best experts on this subject based on the ideXlab platform.
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sequential Nucleophilic Acyl Substitution alkenyl transfer reactions mediated by samarium ii iodide
Journal of Organic Chemistry, 1998Co-Authors: Gary A. Molander, Christina R. HarrisAbstract:Samarium(II) iodide (SmI2) has been employed in a one-pot, three-step, Nucleophilic Acyl Substitution/ketyl−olefin coupling/β-elimination reaction sequence. This novel protocol combines two recently developed SmI2-mediated processes to permit the net delivery of an alkenyl moiety to a ketone carbonyl generated as an intermediate along the sequential reaction pathway. A remarkable measure of stereocontrol over three to five contiguous stereocenters is established in the process as a result of the excellent facial selectivity conveyed in the ketyl−olefin coupling reaction. Unique to the SmI2-mediated process, the relative asymmetric induction engendered in these addition reactions is complementary to more traditional Nucleophilic addition reactions in that the alkenyl group is delivered to the carbonyl center by an attached tether. Moreover, the protocol avoids the basic reaction conditions characteristic of alkenylmagnesium halides and alkenyllithium reagents.
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Sequential Nucleophilic Acyl Substitution/Alkenyl Transfer Reactions Mediated by Samarium(II) Iodide
The Journal of Organic Chemistry, 1998Co-Authors: Gary A. Molander, Christina R. HarrisAbstract:Samarium(II) iodide (SmI2) has been employed in a one-pot, three-step, Nucleophilic Acyl Substitution/ketyl−olefin coupling/β-elimination reaction sequence. This novel protocol combines two recently developed SmI2-mediated processes to permit the net delivery of an alkenyl moiety to a ketone carbonyl generated as an intermediate along the sequential reaction pathway. A remarkable measure of stereocontrol over three to five contiguous stereocenters is established in the process as a result of the excellent facial selectivity conveyed in the ketyl−olefin coupling reaction. Unique to the SmI2-mediated process, the relative asymmetric induction engendered in these addition reactions is complementary to more traditional Nucleophilic addition reactions in that the alkenyl group is delivered to the carbonyl center by an attached tether. Moreover, the protocol avoids the basic reaction conditions characteristic of alkenylmagnesium halides and alkenyllithium reagents.
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sequenced reactions with samarium ii iodide sequential Nucleophilic Acyl Substitution ketyl olefin coupling reactions for the preparation of oxygen heterocycles
Journal of Organic Chemistry, 1997Co-Authors: Gary A. Molander, Christina R. HarrisAbstract:Samarium(II) iodide has been employed to promote a sequential intramolecular Nucleophilic Acyl Substitution/intramolecular ketyl olefin coupling cyclization sequence to provide bicyclic, tricyclic, and spiro-fused oxygen heterocycles in excellent yield and with high diastereoselectivity.
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Sequenced Reactions with Samarium(II) Iodide. Sequential Nucleophilic Acyl Substitution/Ketyl Olefin Coupling Reactions for the Preparation of Oxygen Heterocycles
Journal of Organic Chemistry, 1997Co-Authors: Gary A. Molander, Christina R. HarrisAbstract:Samarium(II) iodide has been employed to promote a sequential intramolecular Nucleophilic Acyl Substitution/intramolecular ketyl olefin coupling cyclization sequence to provide bicyclic, tricyclic, and spiro-fused oxygen heterocycles in excellent yield and with high diastereoselectivity.
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sequenced reactions with samarium ii iodide tandem Nucleophilic Acyl Substitution ketyl olefin coupling reactions
Journal of the American Chemical Society, 1996Co-Authors: Gary A. Molander, Christina R. HarrisAbstract:Samarium(II) iodide has been employed to promote a tandem intramolecular Nucleophilic Acyl Substitution/intramolecular ketyl−olefin coupling cyclization sequence, generating bicyclic, tricyclic, and spirocyclic ring systems in excellent yield and with high diastereoselectivity. This versatile reaction sequence allows entry to several different naturally occurring tricyclic systems containing the angular and linear triquinane framework.
Aleksandr Kasatkin - One of the best experts on this subject based on the ideXlab platform.
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synthesis of 1 hydroxybicyclo n 1 0 alkanes n 3 and 4 and their silyl ethers from olefinic esters via tandem intramolecular Nucleophilic Acyl Substitution and intramolecular carbonyl addition reactions mediated by ti opr i 42 i prmgcl reagent
Tetrahedron Letters, 1996Co-Authors: Aleksandr Kasatkin, Sentaro Okamoto, Katsushige Kobayashi, Fumie SatoAbstract:Abstract Treatment of olefinic esters with Ti(OPr-i)4/2 i-PrMgCl reagent resulted in intramolecular Nucleophilic Acyl Substitution and successive intramolecular carbonyl addition reactions providing 1-hydroxybicyclo[n.1.0]alkanes (n = 3 and 4) in high yields.
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intramolecular Nucleophilic Acyl Substitution reactions mediated by xti o i pr 3 x cl o i pr 2i prmgbr reagent efficient synthesis of functionalized organotitanium compounds from unsaturated compounds
Journal of the American Chemical Society, 1996Co-Authors: Sentaro Okamoto, Aleksandr Kasatkin, P. K. Zubaidha, Fumie SatoAbstract:Treatment of acetylenic or olefinic carbonates and esters with a low-valent titanium reagent diisopropoxy(η2-propene)titanium (1), readily generated by the reaction of Ti(O-i-Pr)4 or ClTi(O-i-Pr)3 with 2i-PrMgX, resulted in an intramolecular Nucleophilic Acyl Substitution (INAS) reaction to afford organotitanium compounds having a carbonyl functional group, in good to excellent yields. Thus, the treatment of alkyl alkynyl carbonates 2 or alkyl alkenyl carbonates 4 with 1 gave organotitanium compounds having a lactone and/or ester group. Similarly, alkyl alkynoates 10 or alkynyl esters 14 of carboxylic acids reacted with 1 to give organotitanium compounds having a cyclic or acyclic ketone group, respectively. Thus, the reaction provides, after hydrolysis, five- or six-membered α-alkylidene lactones and/or α,β-unsaturated esters from 2, γ-butyrolactone derivatives from 4, five- or six-membered α-alkylidene cyclic ketones from 10, and acyclic α,β-unsaturated ketones 15 from 14. In all cases, the yields are e...
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Synthesis of allyltitanium compounds by intramolecular Nucleophilic Acyl Substitution reaction of alka-3,5-dienyl carbonates and their unusual regioselectivity in reaction with aldehydes
Chemical Communications, 1996Co-Authors: P. K. Zubaidha, Aleksandr Kasatkin, Fumie SatoAbstract:Treatment of carbonates of alka-3,5-dien-1-ols with (η2-propene)Ti(OPri)2 resulted in intramolecular Nucleophilic Acyl Substitution (INAS) reaction to afford allyltitanium compounds containing lactone or ester moieties, which add regiospecifically to aldehydes.
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Synthesis of 1-hydroxybicyclo[n.1.0]alkanes (n = 3 and 4) and their silyl ethers from olefinic esters via tandem intramolecular Nucleophilic Acyl Substitution and intramolecular carbonyl addition reactions mediated by Ti(OPr-i)42 i-PrMgCl reagent
Tetrahedron Letters, 1996Co-Authors: Aleksandr Kasatkin, Sentaro Okamoto, Katsushige Kobayashi, Fumie SatoAbstract:Abstract Treatment of olefinic esters with Ti(OPr-i)4/2 i-PrMgCl reagent resulted in intramolecular Nucleophilic Acyl Substitution and successive intramolecular carbonyl addition reactions providing 1-hydroxybicyclo[n.1.0]alkanes (n = 3 and 4) in high yields.
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Intramolecular Nucleophilic Acyl Substitution Reactions Mediated by XTi(O-i-Pr)3 (X = Cl, O-i-Pr)/2i-PrMgBr Reagent. Efficient Synthesis of Functionalized Organotitanium Compounds from Unsaturated Compounds
Journal of the American Chemical Society, 1996Co-Authors: Sentaro Okamoto, Aleksandr Kasatkin, P. K. Zubaidha, Fumie SatoAbstract:Treatment of acetylenic or olefinic carbonates and esters with a low-valent titanium reagent diisopropoxy(η2-propene)titanium (1), readily generated by the reaction of Ti(O-i-Pr)4 or ClTi(O-i-Pr)3 with 2i-PrMgX, resulted in an intramolecular Nucleophilic Acyl Substitution (INAS) reaction to afford organotitanium compounds having a carbonyl functional group, in good to excellent yields. Thus, the treatment of alkyl alkynyl carbonates 2 or alkyl alkenyl carbonates 4 with 1 gave organotitanium compounds having a lactone and/or ester group. Similarly, alkyl alkynoates 10 or alkynyl esters 14 of carboxylic acids reacted with 1 to give organotitanium compounds having a cyclic or acyclic ketone group, respectively. Thus, the reaction provides, after hydrolysis, five- or six-membered α-alkylidene lactones and/or α,β-unsaturated esters from 2, γ-butyrolactone derivatives from 4, five- or six-membered α-alkylidene cyclic ketones from 10, and acyclic α,β-unsaturated ketones 15 from 14. In all cases, the yields are e...
Sentaro Okamoto - One of the best experts on this subject based on the ideXlab platform.
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Practical synthesis of optically active bicyclic oxazolidinylpiperidines, chiral building blocks for preparing 1-deoxyazasugars, from serine
Tetrahedron Letters, 1999Co-Authors: Masaaki Shirai, Sentaro Okamoto, Fumie SatoAbstract:Abstract Optically active bicyclic oxazolidinylpiperidines 1a , 1b , 1c and 1d , known chiral building blocks for preparing 1-deoxyazasugars, were synthesized in high overall yield from D-serine by a method wherein the titanium(II)-mediated intramolecular Nucleophilic Acyl Substitution and FeCl 3 -mediated ring enlargement of bicyclic cyclopropanols are the key reactions.
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Efficient and Practical Method for Synthesizing N-Heterocyclic Compounds Using Intramolecular Nucleophilic Acyl Substitution Reactions Mediated by Ti(O-i-Pr)4/2i-PrMgX Reagent. Synthesis of Quinolones, Pyrroles, Indoles, and Optically Active N-Hetero
Journal of the American Chemical Society, 1997Co-Authors: Sentaro Okamoto, Katsushige Kobayashi, Masayuki Iwakubo, Fumie SatoAbstract:Treatment of N-(2- or 3-alkynyl)amino esters with a low-valent titanium reagent diisopropoxy(η2-propene)titanium (1), generated in situ by the reaction of Ti(O-i-Pr)4 and 2i-PrMgCl, resulted in an intramolecular Nucleophilic Acyl Substitution (INAS) reaction to afford α-alkylidene-pyrrolidinones or -piperidinones. Thus, treatment of N-propargyl-anthranilates 5, -indole-2-carboxylates 10, or -pyrrole-2-carboxylates 13 with 1 gave 4-quinolones 7, [1,2-a]indoles, or [1,2-a]pyrroles, respectively. Similarly, N-alkynylated α- or β-amino esters 14 or 15 with 1 afforded N-heterocycles 18 or 19. In the reaction of N-(2- or 3-alkenyl)amino esters with 1, the resulting INAS product underwent intramolecular carbonyl addition (ICA) reaction to afford the N-heterocyclic compounds having a cyclopropanol moiety in good to excellent yields. Thus, the treatment of N-alkenyl-anthranilate 4a, -indole-2-carboxylates 8 and 9, or -pyrrole-2-carboxylates 11 and 12 with 1 gave the corresponding quinoline derivative 6a, [1,2-a]in...
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Intramolecular Nucleophilic Acyl Substitution Reaction of 3,4-Alkadienyl Carbonates Mediated by Ti(O-i-Pr)4/2 i-PrMgCl Reagent. Efficient Synthesis of Optically Active β,γ-Unsaturated Esters with an α-Substituent
The Journal of organic chemistry, 1996Co-Authors: Yukio Yoshida, Sentaro Okamoto, Fumie SatoAbstract:Treatment of 3,4-alkadienyl carbonates 2a−i with a low-valent titanium reagent diisopropoxy(η2-propene)titanium (1), readily generated by the reaction of Ti(O-i-Pr)4 with 2 i-PrMgCl, resulted in an intramolecular Nucleophilic Acyl Substitution (INAS) reaction to afford vinyltitanium compounds 3 which, in turn, reacted with H3O+, D2O, or iodine to give α-substituted β,γ-unsaturated esters 4 in good to excellent yields. The olefin moiety of the hydrolysis product 4 has (Z)-geometry mainly except for 4h. Starting from chiral 2f or 2g, the reaction proceeded stereospecifically to give optically active α-substituted β,γ-unsaturated ester 4f or 4g having (Z)-olefin geometry exclusively.
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synthesis of 1 hydroxybicyclo n 1 0 alkanes n 3 and 4 and their silyl ethers from olefinic esters via tandem intramolecular Nucleophilic Acyl Substitution and intramolecular carbonyl addition reactions mediated by ti opr i 42 i prmgcl reagent
Tetrahedron Letters, 1996Co-Authors: Aleksandr Kasatkin, Sentaro Okamoto, Katsushige Kobayashi, Fumie SatoAbstract:Abstract Treatment of olefinic esters with Ti(OPr-i)4/2 i-PrMgCl reagent resulted in intramolecular Nucleophilic Acyl Substitution and successive intramolecular carbonyl addition reactions providing 1-hydroxybicyclo[n.1.0]alkanes (n = 3 and 4) in high yields.
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intramolecular Nucleophilic Acyl Substitution reactions mediated by xti o i pr 3 x cl o i pr 2i prmgbr reagent efficient synthesis of functionalized organotitanium compounds from unsaturated compounds
Journal of the American Chemical Society, 1996Co-Authors: Sentaro Okamoto, Aleksandr Kasatkin, P. K. Zubaidha, Fumie SatoAbstract:Treatment of acetylenic or olefinic carbonates and esters with a low-valent titanium reagent diisopropoxy(η2-propene)titanium (1), readily generated by the reaction of Ti(O-i-Pr)4 or ClTi(O-i-Pr)3 with 2i-PrMgX, resulted in an intramolecular Nucleophilic Acyl Substitution (INAS) reaction to afford organotitanium compounds having a carbonyl functional group, in good to excellent yields. Thus, the treatment of alkyl alkynyl carbonates 2 or alkyl alkenyl carbonates 4 with 1 gave organotitanium compounds having a lactone and/or ester group. Similarly, alkyl alkynoates 10 or alkynyl esters 14 of carboxylic acids reacted with 1 to give organotitanium compounds having a cyclic or acyclic ketone group, respectively. Thus, the reaction provides, after hydrolysis, five- or six-membered α-alkylidene lactones and/or α,β-unsaturated esters from 2, γ-butyrolactone derivatives from 4, five- or six-membered α-alkylidene cyclic ketones from 10, and acyclic α,β-unsaturated ketones 15 from 14. In all cases, the yields are e...
