C-CBond Formation by Radical Addition to Alkenes

Hydrocarbon Activation. Synthesis of β-Cycloalkyl (Di)nitriles through Photosensitized Conjugate Radical Addition

“…Infact, as mentioned in the Introduction, synthesis of such compounds via carbanions is unsatisfactory. On the other hand, except for few cases, , most of β-cycloalkylnitriles 3 were obtained by alkylation of unsaturated nitriles through radical methods employing organometallic species, such as stannanes,13a dimeric metal complexes, mercury derivatives, silanes, nickel boride−borohydride exchange resins, in some cases in a better yield than with the present method. However, elimination of metal residues in the final product is troublesome in these cases in view of the low level allowable in drugs, and this makes a metal-free method for generation of radicals desirable.…”

“…On the contrary, β-(cyclo)alkylnitriles have been easily obtained in high yields from the corresponding unsatured nitriles through radical addition reactions. Radicals were generated in different ways: (a) from the corresponding halides via the Giese method with tin or mercury hydrides, as well as from iron, manganese, or chromium complexes; (b) from cyclohexa-2,5-dienylcarboxilic acid precursors; (c) via a photochemical electron-transfer process from 2,2-dialkyldioxolanes, tetraalkylstannanes, , and ammonium salts of phenyl trialkylborates . However, most of the radical methods show several limitations due either to the toxicity of the organometallic species involved or to the tedious synthesis of the radical precursors.…”

Free radical reactions of organomercurials

“…This problem has been overcome by employing 1,1-dicyano olefins 36, as shown in Scheme 38. This procedure is a convenient route to /3,/3-disubstituted carboxylic acids 38 by final hydrolysis of the dicyano derivatives 37 (Table ll). 126 The reaction mechanism included in Schemes 37 and 38 has already been described in Scheme 25. 11 The…”