The vinylogous Mukaiyamaaldolreaction (VMAR) of chiral nonracemic ketene silyl N,O-acetal with various aldehydes is demonstrated. VMAR with α-heteroatom-unsubstituted aldehydes proceeded with a high degree of anti-selectivity. In sharp contrast, moderate to high syn-selectivity was observed when α-heteroatom-substituted aldehydes were used.
Synthesis of homopropargyl alcohols via insertion of allenyl carbenoids into acyclic organozirconium bonds
作者:Jozef Stec、Alan R. Henderson、Richard J. Whitby
DOI:10.1016/j.tetlet.2011.12.081
日期:2012.2
Insertion of allenyl carbenoids (3-tosyloxy-1-lithioalk-1-ynes) into organozirconium complexes gave allenyl-zirconocenes via a 1,2-zirconate rearrangement. Trapping of the allenyl-zirconium species with aldehydes and ketones gave, after hydrolysis, a series of homopropargyl alcohols. Enantioenriched products were prepared by insertion of the lithium carbenoid derived from (S)-but-3-yn-2-yl 4-toluenesulfonate