Chemistry

Detour to Allylic Amines

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Science  29 Jun 2007:
Vol. 316, Issue 5833, pp. 1814
DOI: 10.1126/science.316.5833.1814b

Catalytic olefin and alkyne hydrogenations often proceed through potentially nucleophilic organometallic intermediates, and chemists have recently taken to intercepting such intermediates with a variety of electrophiles. This strategy of carbon-carbon bond formation is appealing from an efficiency standpoint because it eliminates the need to prepare the (often air- and water-sensitive) organometallic nucleophiles stoichiometrically. Barchuk et al. show that an iridium (I) catalyst effectively couples alkyl-substituted alkynes to imine electrophiles during hydrogenation to yield allylic amine products. The reaction proceeds with high selectivity for the E olefin isomer, and also regioselectively places larger alkyl groups closer to nitrogen. This catalyst complements a rhodium analog that proved effective in a range of similar couplings (as summarized recently by Ngai et al.) but led to exclusive hydrogenation of the alkyne in the present system. — JSY

J. Am. Chem. Soc. 129, 10.1021/ja073018j; J. Org. Chem. 72, 1063 (2007).

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