Diastereoselective aziridination of 2-B(pin)-substituted allylic alcohols: an efficient approach to novel organoboron compounds.

We report that 2-B(pin)-substituted allylic alcohols are good substrates for diastereoselective aziridinations in the presence of PhI(OAc)(2) and N-aminophthalimide. Under the aziridination conditions, the valuable B-C bond remains intact, affording a variety of novel boron-substituted aziridines in good yields and excellent diastereoselectivities. Oxidation of the aziridine B-C bond enables generation of syn-1,3-aminohydroxy-2-ketones with high diastereoselectivity.

Catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides with alpha,beta-unsaturated ketones.

Alpha,beta-unsaturated ketones are no longer the missing dipolarophiles in catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides. In the presence of Cu(I)-Fesulphos complexes as catalysts (5 mol %), these substrates combine high reactivity, wide substitution tolerance, moderate to good endo/exo selectivities, and high enantiocontrol. The endo/exo-diastereoselectivity of the reaction is strongly dependent on the cis or trans nature of the enone moiety.

Direct Mannich reaction of glycinate Schiff bases with N-(8-quinolyl)sulfonyl imines: a catalytic asymmetric approach to anti-alpha,beta-diamino esters.

An efficient catalytic enantioselective direct Mannich reaction of glycinate Schiff bases with aryl imines leading to anticonfigured orthogonally protected alpha,beta-diaminoesters has been realized. Keys to success in this new catalyst system are the use of Fesulphos/Cu(CH3CN)4PF6 (3-5 mol%) as a Lewis acid catalyst and readily available N-(8-quinolyl)sulfonyl-protected aldimines as substrates, affording excellent levels of diastereo- (typically anti/syn > 90:10) and enantiocontrol (typically > or = 90% ee). A remarkable feature of this catalyst system is that it allows the construction of products with a tetrasubstituted carbon stereocenter at C-alpha in a highly diastereo- and enantiocontrolled manner.