Addition of Organoboronic Acids to Aldehydes and Imines

Unfortunately, thus far there has been only one example of the asymmetric version of rhodium-catalyzed asymmetric arylation of aldehydes. In this report, by Miyaura [44], a rhodium complex coordinated with axially chiral monodentate phosphine Ug-and, (S)-MeO-mop, catalyzed the addition of phenylboronic acid (2m) to 1-naph- 

Miyaura also [50] reported rhodium-catalyzed additions of arylboronic acids to aldimines. Despite the potential production of water from boronic adds by cydic trimerization, no hydrolysis of N-sulfonyl aldimines was observed when boronic acids were used in the rhodium-catalyzed addition to aldimines in anhydrous diox-ane. The reactions proceeded well, regardless of the presence of both an electron-withdrawing and an electron-donating group on the aldehyde or the arylboronic add. For example, the reaction of N-sulfonyl aldimine 79a with boronic acid 2o catalyzed by cationic rhodium [Rh(cod) MeCN)2]BF4 gave 87% yield of the product 80ao, and 

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