Radical addition reactions of chiral phosphorus hydrides

Tin-Free Radical Reactions Mediated by Organoboron Compounds

“…Parson prepared an alkenyl thiophosphonate by reaction of a chiral thiophosphite with phenylacetylene (Eq. 9c) [29].…”

Radicals in organic synthesis. Part 1

“…A similar reactivity profile is observed with alkynes; the thiophosphite adds to give predominantly Z-alkenes, yet diethyl phosphite fails to undergo any addition. 313 A more detailed study of the various phosphorus reagents found that P]S compounds were more reactive than their P]O counterparts and that phenyl substituents were preferable to ethoxy groups. The reactivity of these reagents mirrored the theoretical bond dissociation energies of the P-H bond calculated by density functional theory (DFT); those compounds with the weakest P-H bond react faster with alkenes.…”

Intermolecular Radical Additions to Alkynes: Cascade‐Type Radical Cyclizations

“…The role of the cycloalkyl clamp in the starting alkyne 67 is to reduce the conformational degrees of freedom in the intermediate highly reactive vinyl radical 69 and to achieve a favorable alignment between the SOMO on the p system and the s-orbital of the respective CÀH bond for the 1,5-HAT. The experiments revealed that the self-terminating cyclization cascade worked best using a cis-1,2-disubstituted cyclopentyl clamp; however, a trans-1,2-disubstituted cyclohexyl ring could also be used.…”

“…However, their intermolecular addition reactions with alkynes are mostly aimed at synthesizing substituted alkenes, 69,70 and only very few cascade reactions that are initiated by P radical addition to C:C triple bonds have been reported. Renaud and coworkers developed a simple one-pot procedure for the cyclization of terminal alkynes mediated by dialkyl phosphites (Scheme 2.35).…”