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Henk Hiemstra - One of the best experts on this subject based on the ideXlab platform.
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expedient pyrrolizidine synthesis by propargylsilane addition to n acyliminium ions followed by gold catalyzed α allenyl amide cyclization
Journal of Organic Chemistry, 2009Co-Authors: Arjen C Breman, J Dijkink, Jan H Van Maarseveen, Sape S Kinderman, Henk HiemstraAbstract:A reaction sequence, involving the addition of (substituted) propargylsilanes to lactam-derived N-acyliminium ions followed by gold-catalyzed cyclization of the resulting α-allenyl amide, is applied in expedient syntheses of pyrrolizidine alkaloids heliotridine and ent-retronecine in five steps from (S)-malic Acid.
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s pyroglutamic Acid s malic Acid and s serine as useful starting materials in the synthesis of enantiopure hydroxyamidines
European Journal of Organic Chemistry, 2000Co-Authors: Martin Ostendorf, Jan Dijkink, Floris P J T Rutjes, Henk HiemstraAbstract:The synthesis of four enantiopure hydroxyamidines is described. One amidine was obtained from (S)-pyroglutamic Acid. Its key step involved the addition of phenylmagnesium bromide to the corresponding ester, affording the tertiary alcohol without detectable racemization. The second amidine was obtained by coupling of an (S)-malic Acid derived N-acyliminium ion with β-naphthol. The other amidines were obtained from an (S)-serine-derived imide which was reduced to two diastereomeric lactams that were eventually transformed into the corresponding amidines.
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Total Synthesis of (+)-Gelsedine.
Angewandte Chemie (International ed. in English), 1999Co-Authors: Winfred G. Beyersbergen Van Henegouwen, Floris P J T Rutjes, Rutger M. Fieseler, Henk HiemstraAbstract:A novel iodide-promoted, allene-terminated cyclization of an N-acyliminium ion, a stereoselective Heck spirocyclization, and a chemoselective demethylation at the nitrogen atom of an oxindole are the key transformations in the first total synthesis of the indole alkaloid (+)-gelsedine (1). This dextrorotatory form of natural gelsedine was formed as a single enantiomer in 21 steps from (S)-malic Acid.
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Studies toward the total synthesis of the oxindole alkaloid gelsedine: an efficient allene-terminated N-acyliminium ion cyclization
The Journal of Organic Chemistry, 1997Co-Authors: W.g. Beijersbergen Van Henegouwen, Henk HiemstraAbstract:This paper reports the synthesis of the advanced intermediate 26 in a projected synthesis of enantiopure ent-gelsedine (5). The route starts from (S)-malic Acid and features the creation of four new stereocenters with complete control of stereochemistry. The key step is a novel allene-terminated N-acyliminium ion cyclization that leads to the required 7-azabicyclo[4.2.1]nonane-4,8-dione skeleton. Additional functionalities including the C-8 ethyl and the C-9 hydroxymethyl are introduced in an efficient manner.
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Studies towards the synthesis of (+)-ptilomycalin A; Stereoselective N-acyliminium ion coupling reactions to enantiopure C-2 substituted lactams
Tetrahedron, 1996Co-Authors: Saskia Louwrier, Henk Hiemstra, Martin Ostendorf, Arnoud Boom, W. Nico SpeckampAbstract:Abstract Highly stereoselective N -acyliminium ion coupling reactions of β-ketoester derived silyl enol ethers with enantiopure lactams derived from ( S )-malic Acid are reported. This reaction type is applied in the synthesis of the enantiopure C-2 substituted lactam 27 , a plausible intermediate in a projected synthesis of ptilomycalin A.
Christopher Glidewell - One of the best experts on this subject based on the ideXlab platform.
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Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines.
Acta Crystallographica Section B Structural Science, 2002Co-Authors: Dorcas M. M. Farrell, George Ferguson, Alan J. Lough, Christopher GlidewellAbstract:(S)-Malic Acid forms a salt with N,N′-dimethylpiperazine, [MeN(CH2CH2)2NMe]H22+·2C4H5O5− (1) (triclinic, P1, Z′ = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4′-bipyridyl, (S)-malic Acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z′ = 1) and (3) (monoclinic, C2, Z′ = 1), while racemic malic Acid with 4,4′-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P21/c, Z′ = 1). In each of (2), (3) and (4) the components are linked by O—H⋯N and N—H⋯O into chains of alternating bipyridyl and malate units, which are linked into sheets by O—H⋯O hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic Acid and racemic malic Acid with 1,2-bis(4′-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180° rotation about the N⋯N vector. In (5), (C12H10N2)H+·C4H5O5− (triclinic, P1, Z′ = 1), the components are again linked by a combination of N—H⋯O and O—H⋯O hydrogen bonds into sheets, while in (6) (triclinic, P{\overline 1}, Z′ = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic Acid forms a 1:2 salt, [(C6H12N2)H2]2+·2C4H5O5− (7) (monoclinic, P21/c, Z′ = 2), while (S)-malic Acid forms a 1:1 adduct, (8) (monoclinic, P21, Z′ = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N—H⋯O and O—H⋯O hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible.
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Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines.
Acta crystallographica. Section B Structural science, 2002Co-Authors: Dorcas M. M. Farrell, George Ferguson, Alan J. Lough, Christopher GlidewellAbstract:(S)-Malic Acid forms a salt with N,N'-dimethylpiperazine, [MeN(CH(2)CH(2))(2)NMe]H(2)(2+) x 2C(4)H(5)O(5)(-) (1) (triclinic, P1, Z' = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4'-bipyridyl, (S)-malic Acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z' = 1) and (3) (monoclinic, C2, Z' = 1), while racemic malic Acid with 4,4'-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P2(1)/c, Z' = 1). In each of (2), (3) and (4) the components are linked by O[bond]H...N and N[bond]H...O into chains of alternating bipyridyl and malate units, which are linked into sheets by O[bond]H...O hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic Acid and racemic malic Acid with 1,2-bis(4'-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180 degrees rotation about the N...N vector. In (5), (C(12)H(10)N(2))H(+) x C(4)H(5)O(5)(-) (triclinic, P1, Z' = 1), the components are again linked by a combination of N[bond]H...O and O[bond]H...O hydrogen bonds into sheets, while in (6) (triclinic, P1;, Z' = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic Acid forms a 1:2 salt, [(C(6)H(12)N(2))H(2)](2+).2C(4)H(5)O(5)(-) (7) (monoclinic, P2(1)/c, Z' = 2), while (S)-malic Acid forms a 1:1 adduct, (8) (monoclinic, P2(1), Z' = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N[bond]H...O and O[bond]H...O hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible.
Pei-qiang Huang - One of the best experts on this subject based on the ideXlab platform.
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Asymmetric Synthesis of (‐)‐(R)‐Pyrrolam A Starting from (S)‐Malic Acid.
ChemInform, 2010Co-Authors: Pei-qiang Huang, Quan Feng Chen, Chang Lin Chen, Hong Kui ZhangAbstract:An asymmetric synthesis of natural (−)-pyrrolam A starting from natural (S)-malic Acid is described. The stereogenic center was established via a highly trans-diastereoselective reductive alkylation procedure. A tandem base-induced intramolecular amide N-substitution and tosic Acid elimination led to the target molecule.
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A concise asymmetric synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate and propionate, the sex pheromones of pine sawflies
The Journal of organic chemistry, 2004Co-Authors: Pei-qiang Huang, Xiao Zheng, Hong-qiao Lan, Yuan-ping RuanAbstract:(2S,3S,7S)-3,7-Dimethylpentadecan-2-yl acetate (2) and its propionate analogue (3) are the main sex pheromones of all Neodiprion species and Diprion similes, respectively. Starting from (S)-malic Acid and employing a highly chemo-, regio-, and stereoselective tandem ester reduction-epoxide formation-reductive epoxide-opening reaction protocol, an efficient total synthesis of (2S,3S,7S)-2 and -3 is reported herein.
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An alternative stereoselective synthesis of protected trans-5-alkyl-4-hydroxy-2-pyrrolidinones
Synthetic Communications, 2000Co-Authors: Pei-qiang Huang, X Tang, Aq ChenAbstract:Abstract A flexible approach to protected trans-5-alkyl-4-hydroxy-2-pyrrolidinones was described. The key step involved the α-amidoalkylation of benzene-sulfone derived from (S)-malic Acid, with organozinc reagents generated in situ from Grignard reagents and anhydrous ZnCl2-OEt2.
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a new approach to s 4 hydroxy 2 pyrrolidinone and its 3 substituted analogues
Tetrahedron-asymmetry, 1999Co-Authors: Pei-qiang Huang, Shi Li Wang, Jian Liang Ye, Xiao Zheng, Zhong ChenAbstract:Abstract Successive treatment of a phenyl thioether derived from ( S )-malic Acid with n- BuLi, lithium naphthalenide (LN), and electrophiles led to 4-hydroxy-3-substituted 2-pyrrolidinones in one-pot and in high regio- and diastereoselectivity at C-3. N -Debenzylation of 1-benzyl-4-hydroxy-2-pyrrolidinone using LN afforded naturally occurring (−)-( S )-4-hydroxy-2-pyrrolidinone. (−)-(3 S ,4 S )-4-Hydroxy-3-methyl-2-pyrrolidinone, the lactam form of the γ-amino Acid residue found in marine natural products, bistramides, was prepared by the same method.
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Asymmetric synthesis of (−)-(R)-pyrrolam A starting from (S)-malic Acid
Tetrahedron: Asymmetry, 1999Co-Authors: Pei-qiang Huang, Quan Feng Chen, Chang Lin Chen, Hong Kui ZhangAbstract:An asymmetric synthesis of natural (−)-pyrrolam A starting from natural (S)-malic Acid is described. The stereogenic center was established via a highly trans-diastereoselective reductive alkylation procedure. A tandem base-induced intramolecular amide N-substitution and tosic Acid elimination led to the target molecule.
Jean-luc Parrain - One of the best experts on this subject based on the ideXlab platform.
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studies towards the total synthesis of caulerpenynol a toxic sesquiterpenoid of the green seaweed caulerpa taxifolia
ChemInform, 2009Co-Authors: Laurent Commeiras, Jérôme Thibonnet, Jean-luc ParrainAbstract:The first diastereoselective synthesis of the antimicrobial and cytotoxic agent (–)-caulerpenynol (2) was achieved in relatively few steps from commercially available (S)-malic Acid. Highlights of this synthesis include the nonracemization of the sensitive α-hydroxy ketone moiety and the proper choice of the protecting groups for critical last deprotection step. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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First Total Synthesis of (‐)‐Caulerpenynol.
ChemInform, 2009Co-Authors: Laurent Commeiras, Jérôme Thibonnet, Jean-luc ParrainAbstract:The first diastereoselective synthesis of the antimicrobial and cytotoxic agent (−)-caulerpenynol 2 has been achieved in relatively few steps from the commercially available (S)-malic Acid.
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Studies Towards the Total Synthesis of (-)-Caulerpenynol, a Toxic Sesquiterpenoid of the Green Seaweed Caulerpa taxifolia
European Journal of Organic Chemistry, 2009Co-Authors: Laurent Commeiras, Jérôme Thibonnet, Jean-luc ParrainAbstract:The first diastereoselective synthesis of the antimicrobial and cytotoxic agent (−)-caulerpenynol 2 has been achieved in relatively few steps from the commercially available (S)-malic Acid. Highlights of this synthesis include the non racemization of sensitive α-hydroxy ketone and the adequate choice of the protecting groups for critical last deprotection step.
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Studies towards the Total Synthesis of (–)-Caulerpenynol, a Toxic Sesquiterpenoid of the Green Seaweed Caulerpa taxifolia†
European Journal of Organic Chemistry, 2009Co-Authors: Laurent Commeiras, Jérôme Thibonnet, Jean-luc ParrainAbstract:The first diastereoselective synthesis of the antimicrobial and cytotoxic agent (–)-caulerpenynol (2) was achieved in relatively few steps from commercially available (S)-malic Acid. Highlights of this synthesis include the nonracemization of the sensitive α-hydroxy ketone moiety and the proper choice of the protecting groups for critical last deprotection step. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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First total synthesis of (-)-caulerpenynol.
Organic & biomolecular chemistry, 2008Co-Authors: Laurent Commeiras, Jérôme Thibonnet, Jean-luc ParrainAbstract:The first diastereoselective synthesis of the antimicrobial and cytotoxic agent (−)-caulerpenynol 2 has been achieved in relatively few steps from the commercially available (S)-malic Acid.
Takamasa Kinoshita - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and stereochemistry of musacins isolated from Streptomyces griseoviridis(FH-S 1832)
Organic & biomolecular chemistry, 2004Co-Authors: Toshihiko Ueki, Takamasa KinoshitaAbstract:Musacins E (1a), B1 (2a) and B2 (3a) have been synthesized starting from D-erythronolactone, L-tartaric Acid and (S)-malic Acid. The absolute stereochemistry of musacins was unambiguously established by this synthesis.
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Stereoselective synthesis and structure of butalactin and lactone II isolated from Streptomyces species
Organic & biomolecular chemistry, 2004Co-Authors: Toshihiko Ueki, Takamasa KinoshitaAbstract:Butalactin (1a) and lactone II (2a) have been synthesized starting from (S)-malic Acid and sorbic Acid by a straightforward route. The absolute stereochemistry of 1a and 2a was unambiguously established by this synthesis.
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Synthesis and absolute configuration of lactone II isolated from Streptomyces sp. Go 40/10
Chemical communications (Cambridge England), 2001Co-Authors: Toshihiko Ueki, Yoshiki Morimoto, Takamasa KinoshitaAbstract:All four possible stereoisomers of lactone II isolated from Streptomyces sp. Go 40/10, an autoregulator, have been efficiently synthesized in a stereoselective manner starting from (S)-malic Acid and sorbic Acid, and the absolute configuration was determined to be 2S, 3S, 9R, 10S.
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Synthesis of hyperolactones A and C
Journal of Heterocyclic Chemistry, 2001Co-Authors: Toshihiko Ueki, Takamasa Kinoshita, Matsumi Doe, Yoshiki Morimoto, Rika Tanaka, Kazuo YoshiharaAbstract:Hyperolactones A (1) and C (3) have been synthesized starting from (S)-malic Acid by a straightforward route. The unique spirolactone skeleton was efficiently constructed by one-pot reaction as a key step. The absolute stereochemistry of hyperolactones was unambiguously established by this synthesis.
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SYNTHESIS AND ABSOLUTE CONFIGURATION OF (-)-MERIDINOL AND (-)-3-EPIMERIDINOL
Journal of Heterocyclic Chemistry, 1999Co-Authors: Daisuke Takano, Takamasa Kinoshita, Matsumi Doe, Yoshiki Morimoto, Kazuo YoshiharaAbstract:The first synthesis of (-)-meridinol and (-)-3-epimeridinol was accomplished from (S)-malic Acid. This synthesis unambiguously established the absolute stereochemistry of meridinol.
