- Enantioselective synthesis of α-alkenyl α-amino acids via N-H insertion reactions
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A new highly enantioselective route to α-alkenyl α-amino acid derivatives, which are important naturally occurring compounds with attractive bioactivity and synthetic utility, was developed using a N-H insertion reaction of vinyldiazoacetates and tert-butyl carbamate cooperatively catalyzed by achiral dirhodium(ii) carboxylates and chiral spiro phosphoric acids under mild, neutral conditions. This reaction has a broad substrate scope, a fast reaction rate (turnover frequency > 6000 h-1), a high yield (61-99%), and excellent enantioselectivity (83-98% ee). The chiral spiro phosphoric acid, which is proposed to realize the enantioselectivity of the insertion reaction by promoting the proton transfer of a ylide intermediate by acting as a chiral proton shuttle catalyst, can suppress several usual side reactions of vinyldiazoacetates and broaden the applications of these versatile carbene precursors in organic synthesis. To our knowledge, it is the first highly enantioselective carbene insertion reaction of vinyldiazoacetates with heteroatom-hydrogen bonds in which the heteroatom has lone-pair electrons.
- Guo, Jun-Xia,Zhou, Ting,Xu, Bin,Zhu, Shou-Fei,Zhou, Qi-Lin
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p. 1104 - 1108
(2016/02/09)
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- Simple Synthesis of L- and D-Vinylglycine (2-Aminobut-3-enoic Acid) and Related Amino Acid
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A three-step synthesis of vinylglycine 1 has been developed using a readily available starting material (but-3-enenitrile 2), based on the Neber rearrangement of the corresponding N-chloroimidate, and using cheap, convenient reagents.Also described is a convenient optical resolution of the N-tert-butoxycarbonyl derivative by papain-catalysed enantioselective esterifucation in a two-phase system.From the optically active amino acid, related amino acids obtained via epoxidation, dihydroxylation and cyclopropanation have been prepared.The related β,γ-unsaturated amino acids (E)-2-aminopent-3-enoic acid 20 and (E)-2-amino-3-methylpent-3-enoic acid 22 have been synthesised using the same approach.
- Hallinan, Keith O.,Crout, David H. G.,Errington, William
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p. 3537 - 3544
(2007/10/02)
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- Polyenolates of unsaturated carboxylic acids in synthesis. Synthesis of unsaturated α-amino acids and γ-hydrazino acids
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Regioselective reaction of lithium diene- and triene-diolates 1 and 2 with o-diphenylphosphinyl hydroxylamine affords unsaturated α-amino acids 3 and 4. Addition to DEAD leads selectively to γ-hydrazino unsaturated acids 5 and 6.
- Aurell,Gil,Martinez,Parra,Tortajada,Mestres
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p. 1833 - 1839
(2007/10/02)
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- ENANTIOSELECTIVE ELECTROPHILIC BOND CONSTRUCTION TO THE α-CARBON OF α-AMINOACIDS
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In this report, we describe three possibilities for aminoacid synthesis using an enantioselective electrophilic process.Thus, enantioselective carboxylation, alkylation and protonation of Schiff bases yield optically active aminoacids with e.e. up to 76percent.
- Duhamel, Lucette,Duhamel, Pierre,Fouquay, Stephane,Eddine, Jamal Jamal,Peschard, Olivier,et al.
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p. 5495 - 5506
(2007/10/02)
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- Allylic Selenides in Organic Synthesis: New Methods for the Synthesis of Allylic Amines
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Oxidative rearrangement of allylic selenides in the presence of various amine nucleophiles provides synthetic access to a variety of allylic amine derivatives.The stereochemical outcome of these reactions has been investigated, and is consistent with a -sigmatropic rearrangement mechanism.Several D-α-amino acids and racemic β,γ-unsaturated α-amino acids were prepared in this manner.A variant of this process employing an achiral allylic selenide and chiral amide afforded protected allylic amines in low diastereoisomeric excess.
- Shea, Regan G.,Fitzner, Jeffrey N.,Fankhauser, John E.,Spaltenstein, Andreas,Carpino, Philip A.,et al.
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p. 5243 - 5252
(2007/10/02)
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- Synthesis of Protected Racemic β,γ-Unsaturated-α-Amino Acids via γ-Phenylseleno-α,β-Unsaturated Esters
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Oxidative rearrangement of γ-phenylseleno-α,β-unsaturated esters (1) with the N-chlorosuccinimide/N,N-diisopropylethylamine/alkyl carbamate reagent combination affords preparatively useful yields of protected β,γ-unsaturated-α-amino acids (2).
- Fitzner, Jeffrey N.,Pratt, Daniel V.,Hopkins, Paul B.
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p. 1959 - 1962
(2007/10/02)
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