A convenient preparation of N-(alkoxycarbonyl)-2,3-didehydroaspartic acid anhydrides 4 with substitution at the 3-position is reported. The key step is a cobalt-mediated acylation of an acetylene moiety, producing the highly functionalized didehydroamine acid derivative in good yield. Unnatural didehydroaspartates are readily accessible.
A One-Pot Synthesis and Functionalization of Polyynes
作者:Yasuhiro Morisaki、Thanh Luu、Rik R. Tykwinski
DOI:10.1021/ol0528888
日期:2006.2.1
[reaction: see text] A one-pot synthesis and derivatization of diynes and triynes is reported. The polyyne framework is formed from a dibromoolefin precursor based on a carbenoid rearrangement, and the resulting Li-acetylide is then trapped in situ with an electrophile to provide functionalized di- and triynes. Alternatively, transmetalation of the Li-acetylide intermediate provides either the Zn-
An enantioselective Pd-catalyzed intramolecular desymmetrizing cycloisomerization of N-(cyclopent-3-en-1-yl)propiolamides has been developed by employing a new chiral phosphoramidite ligand. A series of structurally unique bridged azabicycles are achieved in moderate to excellent yields with good E/Z selectivity and high enantioselectivity. Synthetic transformations are conducted to demonstrate the