Chiral Propargyl Alcohols via the Enantioselective Addition of Terminal Di- and Triynes to Aldehydes
作者:Erin R. Graham、Rik R. Tykwinski
DOI:10.1021/jo2008719
日期:2011.8.19
The enantioselective addition of di- and triynes to aldehydes is presented, including the first examples of an asymmetric triyne addition. Modification of the Carreira alkynylation protocol shows that addition of diynes and triynes to alpha-branched aldehydes can be complete in as little as 4 h, and these reactions give good yields and enantioselectivities (up to 98% ee) for di- and triynes tested (aryl, alkyl, and silyl). It is shown for two cases (20 and 24) that products of this asymmetric addition reaction can undergo further manipulation (desilylation and triazole formation) without affecting the enantiopurity.
Regioselective Trapping of Terminal Di-, Tri-, and Tetraynes with Benzyl Azide
作者:Thanh Luu、Robert McDonald、Rik R. Tykwinski
DOI:10.1021/ol062522a
日期:2006.12.1
The reaction of benzyl azide with terminal di-, tri-, and tetraynes appended with a range of functional groups has been explored. Standard reaction conditions for BnN3 catalyzed by CuSO(4)(.)5H(2)O gave alkynyl, butadiynyl, and hexatriynyl triazoles in moderate to good yields. The reaction proceeds regioselectively as determined by the X-ray crystallographic analysis of three derivatives (1c, 1d, and 3c), and no evidence of multiple azide addition to the polyyne framework is observed.