cis-Selective Hydroboration ofAllenes

Significance The authors report a hydroboration of allenes giving Z -alkenes. Subsequent allylboration can be carried out in high diastereo- and enantioselectivity. Access to these alkenes through hydroboration is difficult because of competing isomerization to the thermodynamically favored E -alkenes. The use of the Soderquist borane 2 is noteworthy (J. A. Soderquist and co-workers J. Am. Chem. Soc. 2008 , 130 , 9218). Review: For a review on allylboration, see: D. G. Hall Pure Appl. Chem. 2008 , 80 , 913-927.