Silver(I)-Catalyzed Aminocyclization of 2,3-Butadienyl and 3,4-Pentadienyl Carbamates: An Efficient and Stereoselective Synthesis of 4-Vinyl-2-oxazolidinones and 4-Vinyltetrahydro-2<i>H</i>-1,3-oxazin-2-ones
作者:Masanari Kimura、Shuji Tanaka、Yoshinao Tamaru
DOI:10.1246/bcsj.68.1689
日期:1995.6
Silver(I) salts in combination with an appropriate base (mostly triethylamine) catalyzed the aminocyclization of N-substituted 2,3-butadienyl carbamates 1 (benzene, 50 °C) to provide 4-vinyl-2-oxazolidinones 2 in good yields. The stereoselectivity (trans-2/cis-2) ranged from 1.4 for C5-Me to >30 for C5-phenyl, isopropenyl, and t-butyl derivatives. 3,4-Pentadienyl tosylcarbamates 3, the one-carbon higher homologues of 1, underwent a similar cyclization to give 4-vinyltetrahydro-2H-1,3-oxazin-2-one 4 in synthetically useful yields and in higher trans selectivities than 1.
Synthesis of Functionalized [3], [4], [5] and [6]Dendralenes through Palladium‐Catalyzed Cross‐Couplings of Substituted Allenoates
作者:Daniel J. Lippincott、Roscoe T. H. Linstadt、Michael R. Maser、Bruce H. Lipshutz
DOI:10.1002/anie.201609636
日期:2017.1.16
A mild method for the synthesis of highly functionalized [3]–[6]dendralenes is reported, representing a general strategy to diversely substituted higher homologues of the dendralenes. The methodology utilizes allenoates bearing various substitution patterns, along with a wide range of boron and alkenyl nucleophiles that couple under palladium catalysis leading to sp‐, sp2‐, and sp3‐substituted arrays