Liebigs Annalen p. 141 - 154 (1997)
Update date:2022-08-03
Topics:
Braun, Manfred
Opdenbusch, Kersten
The chiral vinyllithium reagent (S)-1b, readily generated from dibromoalkene (S)-1a by bromine/lithium exchange, adds stereoselectively to mesitylsulfonylimines 2a-f so that the diastereomers 3 are obtained in ≥98% d.e. after column chromatography. The bromoalkenes 3a-d are submitted to ozonolysis in methanol to give α-mesitylsulfonylamino esters (S)-8a-d which can be hydrolyzed to deliver N-protected α- amino acids in >95% e.e. On the other hand, α-mesitylsulfonylamino aldehydes 12a-d are available when bromoalkenes 3a, d-f are first debrominated (→ 11a-d) and subsequently ozonized. In order to avoid reacemization, the aldehydes 12a-d are not purified but submitted to a Mukaiyama-type aldol addition whereby hydroxyesters 15a-d are formed as single diastereomers in a chelate-controlled reaction. The relative configuration of the esters 15a-d is proven by conversion into the oxazolidinones 16a-d whose optical purity is determined to exceed 92% e.e. by 1H-NMR measurements in the presence of chiral shift reagents. The sulfonylimine 21a and a series of para-substituted derivatives 21b-h are also allowed to react with the vinyllithium reagent 1b to give mixtures of diastereomers 22/23. The logarithms of the diastereomeric ratios 22:23 correlate with Hammett's σ-values. VCH Verlagsgesellschaft mbH, 1997.
View MoreZhejiang Kente Chemical Co.,Ltd.
Contact:86-0576-87651912
Address:No.7, Fengxi West Road, Modern Industrial Zone
Jiangxi Hito Chemical Co., Ltd.
Contact:+86-792-3170318
Address:No. 6, Tianhong Ave., Xinghuo Industry Park, Yongxiu, Jiujiang, Jiangxi, China
Shandong Loyal Chemical industrial Co.,Ltd
Contact:0533-7451788
Address:Linzi Chemical Industrial Park, Zibo, Shandong Province
TAIXING BEST NEW MATERIALS CO., LTD
Contact:0523-87998158;
Address:No.18 Zhonggang Road,Taixing City ,Jiangsu , China
Qingdao Kingway Pharmtech Co., Ltd.
Contact:86-532-87118899
Address:No. 88, Middle Haixi Road, Jiaonan City, Qingdao, China
Doi:10.1021/jacs.5b04168
(2015)Doi:10.1039/c39920001176
(1992)Doi:10.1016/j.dyepig.2014.07.024
(2015)Doi:10.1080/10426507.2012.729236
(2013)Doi:10.1021/ol401547d
(2013)Doi:10.1016/S0040-4039(00)60024-2
(1992)