Telomers from Carbon Monoxide and Olefins

Radical and radical-ionic multicomponent processes

All in one pot! Radical, radical-ionic, and radical-organometallic MCR are highly convergent processes, representing a useful pathway to molecular and structural diversity (see scheme). This concept article highlights recent developments in the field and shows the potential of the strategy for the economical elaboration of various kinds of organic substrates.Progress in multicomponent reactions (MCRs) based on ionic and organometallic processes has recently allowed the synthesis, with high efficiency, of large collections of drug-like molecules. In contrast, MCRs based on cascade radical reactions appear to have attracted, so far, much less interest. This concept article highlights the latest progress in the field and underlines the potential of such an approach. The collected examples demonstrate that radical and radical-ionic MCRs are highly convergent processes leading to useful structural diversity.

Theoretical Study on the Isomerization Behavior between α,β-Unsaturated Acyl Radicals and α-Ketenyl Radicals

[reaction: see text] Ab initio calculations using 6-311G**, cc-pVDZ, aug-cc-pVDZ, and a (valence) double-zeta pseudopotential (DZP) basis set, with (QCISD, CCSD(T)) and without (UHF) the inclusion of electron correlation, and density functional methods (BHandHLYP, B3LYP) predict that alpha,beta-unsaturated acyl radicals and alpha-ketenyl radicals exist as isomers. At the CCSD(T)/cc-pVDZ//BHandHLY/cc-pVDZ level of theory, energy barriers of 15.1 and 17.7-21.7 kJ mol(-)(1) are calculated for the isomerization of s-trans-propenoyl and s-trans-crotonoyl radical to ketenylmethyl and 1-ketenylethyl radical, respectively. Similar results are obtained for the reactions of s-trans isomers involving silyl, germyl, and stannyl groups with energy barriers (DeltaE++) of 12.2-12.4, 13.1-13.9, and 12.9-18.2 kJ mol(-)(1) at the CCSD(T)/DZP//BHandHLYP/DZP calculation, respectively. These results suggest that alpha,beta-unsaturated acyl radicals and alpha-ketenyl radicals are not canonical forms but are isomeric species that can rapidly interconvert.

Group Transfer Carbonylations: Photoinduced Alkylative Carbonylation of Alkenes Accompanied by Phenylselenenyl Transfer

The photolysis of methyl alpha-(phenylseleno)acetate (1b) and related compounds in the presence of an alkene and CO leads to acyl selenides 2 via group transfer carbonylation. The mechanism of this three-component coupling reaction involves the addition of a (methoxycarbonyl)methyl radical to an alkene, the trapping of the produced alkyl free radical by CO, and termination of the reaction by a phenylselenenyl group transfer from the starting material.