2013-12-9Relevant articles and documents
Enantioselective synthesis of α-alkenyl α-amino acids via N-H insertion reactions
Guo, Jun-Xia,Zhou, Ting,Xu, Bin,Zhu, Shou-Fei,Zhou, Qi-Lin
, p. 1104 - 1108 (2016)
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.
Stereodivergent addition of allylmetal reagents to imines derived from (R)2,3-Di-O-benzylglyceraldehyde by appropriate selection of metal and double stereodifferentiation
Badorrey, Ramon,Cativiela, Carlos,Diaz-de-Villegas, Maria D.,Diez, Roberto,Galvez, Jose A.
, p. 3763 - 3767 (2002)
The addition of allylmetal reagents to N-benzylimines derived from (R)-2,3-di-O-benzylglyceraldehyde has been achieved with high yields and diastereoselectivities. Homoallylamine 2a of syn configuration is obtained preferentially with allylmagnesium bromide, whereas homoallylamine 2a of anti configuration is obtained as the major reaction product with allyl-9-borabicyclo[3.3.1]nonane. Appropriate combinations of the allylmetal reagent and imines derived from (R)-2,3-di-O-benzylglyceraldehyde and (S)- or (R)-1-phenylethylamine afforded syn or anti homoallylamines with total stereocontrol through double stereodifferentiation processes. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
One-Pot Preparation of d-Amino Acids Through Biocatalytic Deracemization Using Alanine Dehydrogenase and Ω-Transaminase
Han, Sang-Woo,Shin, Jong-Shik
, p. 3678 - 3684 (2018/10/20)
d-Amino acids are pharmaceutically important building blocks, leading to a great deal of research efforts to develop cost-effective synthetic methods. Preparation of d-amino acids by deracemization has been conceptually attractive owing to facile synthesis of racemic amino acids by Strecker synthesis. Here, we demonstrated biocatalytic deracemization of aliphatic amino acids into d-enantiomers by running cascade reactions; (1) stereoinversion of l-amino acid to a d-form by amino acid dehydrogenase and ω-transaminase and (2) regeneration of NAD+ by NADH oxidase. Under the cascade reaction conditions containing 100?mM isopropylamine and 1?mM NAD+, complete deracemization of 100?mM dl-alanine was achieved after 24?h with 95% reaction yield of d-alanine (> 99% eeD, 52% isolation yield). Graphical Abstract: [Figure not available: see fulltext.].
Asymmetric Transamination of α-Keto Acids Catalyzed by Chiral Pyridoxamines
Lan, Xiaoyu,Tao, Chuangan,Liu, Xuliang,Zhang, Aina,Zhao, Baoguo
supporting information, p. 3658 - 3661 (2016/08/16)
A new type of novel chiral pyridoxamines 3a-g containing a side chain has been developed. The pyridoxamines displayed catalytic activity and promising enantioselectivity in biomimetic asymmetric transamination of α-keto acids, to give various α-amino acids in 47-90% yields with up to 87% ee's under very mild conditions. An interesting effect of the side chain on enantioselectivity was observed in the reaction.
