A new protocol of protection of poorly reactive aryl amines and functionalized amines with Boc 2 O in the presence of Zn(ClO 4 ) 2 •6H 2 O as the catalyst is reported. The catalytic action of Zn(ClO 4 ) 2 •6H 2 O is specific for the activation of the pyrocarbonates, thus acid sensitive functionalities and stereochemical configurations of the starting materials remain unaltered in the protection process.

[reaction: see text] A new mild method for protecting alcohols as t-butyl ethers is reported. The reaction proceeds with Mg(ClO4)2 and Boc2O and shows general applicability. The deprotection of t-butyl ethers has also been revisited. Preliminary results indicate the CeCl3 x 7H2O/NaI system is a very suitable catalyst for their removal.

[reaction: see text] The first asymmetric aminolysis of trans-aromatic epoxides with anilines is described. The process affords enantioenriched anti-beta-amino alcohols in up to 99% ee. The complete regio- and diastereoselectivity observed uses commercially available [Cr(Salen)Cl] as a Lewis acid catalyst and in combination with a very simple experimental procedure renders the present reaction a facile and practical tool for the synthesis of chiral nonracemic anti-beta-amino alcohols.

The use of a bifunctional Cinchona alkaloid catalyst has provided a new organocatalytic strategy for the enantioselective addition of diphenylphosphine to a range of nitroalkenes, affording optically active beta-nitrophosphines (up to 99% ee after crystallization); this organocatalytic approach, providing a direct route to a new class of potentially useful enantiopure P,N-ligands, constitutes a bridge between the two complementary areas of asymmetric catalysis: organo- and metal-catalyzed transformations.

Dedicated to Professor Achille Umani-Ronchi on the occasion of his 70th birthdayThe enantioselective construction of quaternary stereogenic centers bonded to four carbon atoms by efficient asymmetric methods is a great synthetic challenge, as the creation of such complex fragments is complicated by steric factors.[1] Currently, despite the substantial progress that has been made in the last few years, only a few catalytic asymmetric CÀC bondforming strategies have proven to be useful for forming quaternary carbon centers.[2] Among them, the catalytic conjugate addition [3] of compounds with a prochiral trisubstituted nucleophilic carbon atom to b-substituted Michael acceptors constitutes an effective approach for the asymmetric construction of highly functionalized products with adjacent quaternary and tertiary carbon centers. The stereocontrolled, one-step synthesis of such important congested motifs from simple precursors is a formidable synthetic challenge, as the catalyst must provide high levels of stereoselectivity in a sterically demanding CÀC bond-forming process.[4] To date, the acceptors employed in this powerful type of strategy have been enones, [5] nitroalkenes, [6] and unsaturated imides. [7] Expansion of the scope of such an efficient strategy to other classes of Michael acceptors is a useful and challenging objective.Herein, we report the development of the first asymmetric direct conjugate addition of 1,3-dicarbonyl compounds to