Steric effects stereoselective electron transfer

Cyclic voltammetry, kinetic studies, and DFT calculations using a BP functional and the TZVP basis set showed that the major pathway of the non-regiospeciflc zinc-reduced titanocene-mediated ring opening of epoxides was initiated by a titanium dimer-epoxide compound that reacted in a rate-determining electron transfer mechanism 25 The calculations showed that the transition state is early so the stereoselectivity is determined by steric effects rather than by the stability of intermediate radicals. This was confirmed by studies with more sterically crowded catalysts. 

N. Okamura, M. Kawai, Y. 1998 J. Am. Chem. Soc. 120, 1186-1192 NAD(P)+-NAD(P)H Models. 88. Stereoselection without steric effect but controlled by electronic effect of a carbonyl group Syn/Anti reactivity ratio, kinetic isotope effect, and an electron-transfer complex as a reaction intermediate. 

NAD(P)H. 32. Stereoselective reduction of camphoroquinone by a chiral NAD(P)H model. Bull Chem Soc Jpn 54 3478-3481 Ohno A, Nakai J, Nakamura K, Goto T, Oka S (1981c) Reduction by a model of NAD(P)H. 33. Steric and electronic effects on asymmetric reduction of 2-acylpyridines. Bull Chem Soc Jpn 54 3482-3485 Ohno A, Yamamoto H, Oka S 0 981d) Reduction by a model of NAD(P)H. 35. Spectroscopic detection of charge-transfer intermediate. Bull Chem Soc Jpn 54 3489-3491... 

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