Synthesis of Jenamidines A<sub>1</sub>/A<sub>2</sub>
作者:Barry B. Snider、Jeremy R. Duvall
DOI:10.1021/ol0518784
日期:2005.9.1
[reaction: see text] Addition of the enolate of tert-butylacetate to cyanamide methyl ester 17 followed by treatment with LHMDS afforded vinylogous urea 19 in 27% yield. Vinylogous urea 19 was also obtained from 37 and tert-butyl cyanoacetate in 50% yield. Acylation of 19 with acid chloride 31d, followed by hydrolysis of the tert-butylester and decarboxylation with 9:1 CH2Cl2/TFA and very mild basic
Structure Reassignment and Synthesis of Jenamidines A<sub>1</sub>/A<sub>2</sub>, Synthesis of (+)-NP25302, and Formal Synthesis of SB-311009 Analogues
作者:Jeremy R. Duvall、Fanghui Wu、Barry B. Snider
DOI:10.1021/jo061650+
日期:2006.10.1
and C (8-10). Jenamidines A(1)/A(2) (8) were synthesized from activated proline derivative 43 by conversion to 26 in two steps and 50% overall yield. Acylation of 26 with acid chloride 38d gave 39d, which was deprotected with TFA and then mild base to give 8 in 45% yield from 26. (-)-trans-2,5-Dimethylproline ethyl ester (49) was prepared by the enantioselective Michael reaction of ethyl 2-nitropropionate (51) and methyl vinyl ketone (50) using modified dihydroquinine 60 as the catalyst. Further elaboration converted 49 to natural (+)-NP25302 (12). A Wittig reaction of proline NCA ( 76) with ylide 79 gave 72 as a 9/1 E/Z mixture in 27% yield, completing a one-step formal synthesis of SB-311009 analogues.