A highly efficient and enantioselective Ir-catalyzed hydrogenation of unsaturated sulfones was developed. Chiral cyclic and acyclic sulfones were produced in excellent enantioselectivities (up to 98% ee). Coupled with the Ramberg-Bäcklund rearrangement, this reaction offers a novel route to chiral allylic and homoallylic compounds in excellent enantioselectivities (up to 97% ee) and high yields (up to 94%).

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A direct synthesis of γ‐oxo‐α,β‐unsaturated esters has been developed. When heteroaromatic aldehydes are reacted with deprotonated ethyl propiolate, in the presence of Me2Zn or BuLi, the newly formed propargylic alcohol rearranged spontaneously to give the corresponding unsaturated keto ester. Isotope labeling, allenol intermediate trapping and crossover experiments provided insight into the reactive sequence and suggest an autocatalytic mechanism.

Compounds. -The highly efficient hydrogenation of various unsaturated cyclic and acyclic sulfones in the presence of IRC coupled with Ramberg-Baecklund rearrangement offers a novel access to the target compounds. -(ZHOU, T.; PETERS, B.; MALDONADO, M. F.; GOVENDER, T.; ANDERSSON*, P. G.; J. Am. Chem. Soc. 134 (2012) 33, 13592-13595, http://dx.doi.org/10.1021/ja306731u ; Dep. Chem., Uppsala Univ., S-751 23 Uppsala, Swed.; Eng.) -Mais 09-168