Synthesis of functionalized CF3-containing heterocycles via [2,3]-sigmatropic rearrangement and sequential catalytic carbocyclization

A new efficient access to functionalized CF3-substituted and nitrogen or sulfur-containing heterocycles has been developed directly from diazocompounds CF3C(N-2)Z (Z=CO2Me, P(O)(OEt)(2)). The method is based on the direct selective synthesis of doubly unsaturated substrates followed by metal-mediated carbocylization. The first step has been performed by Cu(II)-catalyzed [2,3]-sigmatropic rearrangement of propargyl- or/and allyl-containing sulfur and nitrogen ylides leading to fluorinated enynes, diolefins, and especially allenynes derivatives. The second step involves their carbocyclization via ring closing metathesis and Pauson-Khand reaction. (c) 2011 Elsevier Ltd. All rights reserved.