Zinc catalysis Michael addition

C ampelo, JM Climeiu. MS Marinas, JM. Michael addition of niiromcihanc to 3-buten-2-onc catalyzed by pinassium fluoride supported on alumina, zinc oxide, tin dioxide, scpiolilc, aluminum phosphate. AlP04-AI Oi and AIP04-ZnO. Reaction Kinetics and Catalysis Letters. 1992 47, 7-11. 

B.M. Trost, J. Hitce, Direct asymmetric Michael addition to nitroalkenes vinylogous nudeophiUcity under dinudear zinc catalysis, J. Am. Chem. Soc. 131 (2009) 4572-4573. 

During the last decade, use of oxazaborolidines and dioxaborolidines in enantioselective catalysis has gained importance. [1, 2] One of the earliest examples of oxazaborolidines as an enantioselective catalyst in the reduction of ketones/ketoxime ethers to secondary alco-hols/amines was reported by Itsuno et al. [3] in which (5 )-valinol was used as a chiral ligand. Since then, a number of other oxazaborolidines and dioxaborolidines have been investigated as enantioselective catalysts in a number of organic transformations viz a) reduction of ketones to alcohols, b) addition of dialkyl zinc to aldehydes, c) asymmetric allylation of aldehydes, d) Diels-Alder cycloaddition reactions, e) Mukaiyama Michael type of aldol condensations, f) cyclopropana-tion reaction of olefins. 

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