Here, we present a new strategy for the totalsynthesis based upon a skipped diyne as central building block. This was transformed so far into an advanced intermediate related to the pharmacophore of the jerangolids.
Various cerium allenyl reagents were generated by trans- metallation of allenyl Grignard compounds with CeCl3 and sub- sequent conversion into homopropargylic alcohols by addition to various aliphatic and aromatic aldehydes. The a-acetylenic alcohols were obtained with regioselectivities and diastereoselectivities up to 98% de in favor of the threo-diastereomers.
The Renaissance of an Old Problem: Highly Regioselective Carboxylation of 2-Alkynyl Bromides with Carbon Dioxide
作者:Bukeyan Miao、Gen Li、Shengming Ma
DOI:10.1002/chem.201503494
日期:2015.11.23
A steric effect‐controlled, zinc‐mediated carboxylation of different 2‐alkynyl bromides under an atmosphericpressure of CO2 has been developed by careful tuning of different reaction parameters, including the metal, solvent, temperature, and additive. 2‐Substituted 2,3‐allenoic acids were afforded from primary 2‐alkynyl bromides, whereas the carboxylation of secondary 2‐alkynyl bromides yielded 3‐alkynoic
Diastereoselective and Enantioselective Synthesis of Homopropargyl and Allenylcarbinols from Nonracemic Propargyl Mesylates via the Derived Allenyl and Propargyl Trichlorosilanes