ZrCl4/Hantzsch 1,4-dihydropyridine is a mild and highly efficient reagent combination for the direct reductive amination. Weakly basic amines such as anilines substituted by electron-withdrawing group and heteroaromatic amines can be reductively alkylated with electron rich aldehydes and ketones under mild conditions to form the secondary amines in excellent yields.
The organic chemistry of polyvalent iodine compounds has experienced an unprecedented development during the last decade of 20th century.[1,2] On the other hand, despite its extensive use in industry, I2O5 (iodine pentoxide, IP) has rarely been employed in organic synthesis except as an alternative to iodoxybenzoic acid (IBX) for the dehydrogenation of aldehydes and ketones.[3] Generally, pentavalent iodine reagents, such as IBX and Dess-Martin periodinane (DMP)were used as mild and selective oxidants for oxidation of alcohols[1,2] and dehydrogenation of carbonyl compounds.[3] We wish to report herein that IP can serve as a mild and efficient reagent for the oxidative cleavage of oximes to aldehydes and ketones (Eq. 1). Most interestingly, IP can also activate hydrosilanes for reduction of alkenes. Hence, simultaneous deoximation and conjugate reduction of α,β-unsaturated ketoximes can be achieved by using IP and phenyldimethylsilane (Eq. 2).……
