Highly Enantioselective Addition of Phenylacetylene to Aldehydes Catalyzed by a Camphorsulfonamide Ligand
作者:Zhaoqing Xu、Chao Chen、Jiangke Xu、Mingbo Miao、Wenjin Yan、Rui Wang
DOI:10.1021/ol036418u
日期:2004.4.1
The asymmetricaddition of phenylacetylene to aldehydes was carried out by using a camphorsulfonamide titanium complex as a catalyst. The reactions proceeded under mild conditions and gave the products with good yields and high ees. This system is very useful for the synthesis of chiral propargylic alcohol. [reaction: see text]
Asymmetric Addition of Phenylacetylene to Aldehydes Catalyzed by β-Sulfonamide Alcohol-Titanium Complex
作者:Zhaoqing Xu、Li Lin、Jiangke Xu、Wenjin Yan、Rui Wang
DOI:10.1002/adsc.200505453
日期:2006.3
A series of β-sulfonamide alcohol ligands were synthesized from L-phenylalanine. Titanium complexes of these compounds were used to catalyze the asymmetricaddition of phenylacetylene to a number of aldehydes. When the conditions were optimized, 20 mol % of ligand 8a catalyzed the reaction with high enantioselectivity (up to 98% ee) and good yield (up to 92%). When a small amount of MeOH was added
A Concise Synthesis of (S)-(+)-Ginnol Based on Catalytic Enantioselective Addition of Commercially Unavailable Di(n-alkyl)zinc to Aldehydes and Ketones
作者:Kazuaki Ishihara、Manabu Hatano、Tomokazu Mizuno
DOI:10.1055/s-0030-1258129
日期:2010.8
Catalytic, enantioselective n-alkyl addition of commercially unavailable di(n-alkyl)zinc reagents, which were prepared by a refined version of Charette's procedure with Grignard reagents, to aldehydes and ketones was developed. To minimize the side reactions in the catalysis by chiral phosphoramide ligand (1) or 3,3'-diphosphoryl-BINOL ligand (2), a preparation of di(n-alkyl)zinc reagents with a 1:2
Utilization of whole cell mediated deracemization in a chemoenzymatic synthesis of enantiomerically enriched polycyclic chromeno[4,3-b] pyrrolidines
作者:Thangavelu Saravanan、Sushital Jana、Anju Chadha
DOI:10.1039/c4ob00615a
日期:——
Various aryl and alkyl substituted optically pure propargyl alcohols were obtained with excellent ee (up to >99%) and isolated yields (up to 87%) by deracemization using whole cells of Candida parapsilosis ATCC 7330. The whole cells show substrate specificity towards alkyl substituted propargyl alcohols and a switch in the enantioselectivity has been observed from ‘R’ to ‘S’ upon increasing the chain
通过使用副念珠菌ATCC 7330的全细胞进行消旋,获得了各种具有芳烃和烷基取代基的光学纯炔丙醇,具有优异的ee(最高> 99%)和分离的收率(最高87%)。整个细胞显示出对烷基取代的底物特异性随着链长的增加,已观察到炔丙醇和对映选择性的变化,从“ R ”变为“ S ”。对映体纯(R)-4-(3-羟基丁-1-炔基)苄腈,(R)-4-(联苯-4-基)丁-3-炔-2-醇,(S)- 3-羟基-5-苯基戊-4-酸乙酯和(S使用该策略获得了)-4-苯基丁-3-炔-1,2-二醇。如此获得的光学纯的炔丙醇用作手性起始原料,成功合成了对映体富集的多取代的吡咯烷和吡咯衍生物,成功地证明了化学酶促路线。
Enantioselective addition of phenylacetylene to aldehydes catalyzed by polymer-supported titanium(IV) complexes of β-hydroxy amides
A series of polymer‐supported chiral β‐hydroxy amides and C2‐symmetric β‐hydroxy amides have been synthesized and successfully used for the enantioselective addition of phenylacetylene to aldehydes. High yields (up to 93%) and enantioselectivities (up to 92% ee) were achieved by using polymer‐supported chiral β‐hydroxy amide 4b. The resin 4b is reused four times, giving the product with enantioselectivity