Studies of N-terminal templates for .alpha.-helix formation. Synthesis and conformational analysis of (2S,5S,8S,11S)-1-acetyl-1,4-diaza-3-keto-5-carboxy-10-thiatricyclo[2.8.1.04,8]tridecane (Ac-Hel1-OH)
作者:D. S. Kemp、Timothy P. Curran、William M. Davis、James G. Boyd、Christopher Muendel
DOI:10.1021/jo00023a037
日期:1991.11
A convergent synthesis of the title compound, a conformationally restricted analogue of acetyl-L-prolyl-L-proline, from 1-acetyl-2(S)-carboxy-4(S)-mercaptopyrrolidine and trans-1-(tert-butoxycarbonyl)-2(S)-(methoxy-carbonyl)-5(S)-[(tosyloxy)methyl]pyrrolidine (Ac-Hel1-OH) is reported, along with a synthesis of (2S,8S,11S)-1-acetyl-1,4-diaza-3-keto-10-thiatricyclo[2.8.0(4,8)]tridecane. In the crystal and in CDCl3 solution the conformation of Ac-Hel1-OH is shown to approximate a staggered orientation at the 8,9-CC bond and an s-cis orientation at the acetyl amide bond. In DMF, DMSO, MeCN, and D2O significant amounts of the s-trans conformer are also present.