Regioselective Reduction of NAD+ Models with [Cp*Rh(bpy)H]+ : Structure-Activity Relationships and Mechanistic Aspects in the Formation of the 1,4-NADH Derivatives.

The hydride transfer mechanism of the NAD+ model compound 1 to its 1,4-NADH derivative 3 [Eq. (1)] is proposed to be a consequence of the critical role of the carbonyl group of the amide to coordinate to the ring-slipped η5 - to η3 -Cp*Rh metal center of the catalyst [Cp*Rh(bpy)H]+ , prepared in situ from 2, while a steric effect of a substituent in the 3 position, for example, C(O)NEt2 , was found to totally inhibit this regioselective reduction. bpy=2,2'-bipyridine, Cp*=C5 Me5 , OTf=trifluoromethanesulfanate. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.