Structurally Defined Molecular Hypervalent Iodine Catalysts for Intermolecular Enantioselective Reactions
作者:Stefan Haubenreisser、Thorsten H. Wöste、Claudio Martínez、Kazuaki Ishihara、Kilian Muñiz
DOI:10.1002/anie.201507180
日期:2016.1.4
Molecular structures of the most prominent chiral non‐racemic hypervalent iodine(III) reagents to date have been elucidated for the first time. The formation of a chirally induced supramolecular scaffold based on a selective hydrogen‐bonding arrangement provides an explanation for the consistently high asymmetric induction with these reagents. As an exploratory example, their scope as chiral catalysts
Chemoenzymatic synthesis of enantiomerically pure terminal 1,2-diols
作者:Ahmed Kamal、Mahendra Sandbhor、Kaleem Ahmed、S.F. Adil、Ahmad Ali Shaik
DOI:10.1016/j.tetasy.2003.09.035
日期:2003.12
A new practical method for the enzymatic synthesis of 1,2-diols has been developed by employing a lipase catalyzed one-pot transesterification protocol. A series of substituted α-acetoxyphenylethanones 3a–g have been reduced to the corresponding alcohols under mild conditions employing sodium borohydride and moist neutral alumina, and further subjected for lipase catalyzed irreversible transesterification
An enantioselective catalytic vicinal diamination of styrenes is reported, which proceeds under entirely intermolecular reaction control. It relies on a chirally modified aryliodine(I) catalyst and proceeds within an iodine(I/III) manifold with conventional 3-chloroperbenzoic acid as a terminal oxidant. An environmentally benign solvent combination not only adds to the attractiveness of the process
Enantioselective Prévost and Woodward reactions using chiral hypervalent iodine(iii): switchover of stereochemical course of an optically active 1,3-dioxolan-2-yl cation
Optically active 1,3-dioxolan-2-yl cation intermediates were generated during enantioselective dioxyacetylation of alkene with chiral hypervalent iodine(III). Regioselective attack of a nucleophile toward the intermediate resulted in reversal of enantioselectivity of the dioxyacetylation.
ZrCl<sub>4</sub> as an Efficient Catalyst for a Novel One-Pot Protection/Deprotection Synthetic Methodology
作者:Surendra Singh、Colm D. Duffy、Syed Tasadaque A. Shah、Patrick J. Guiry
DOI:10.1021/jo800932t
日期:2008.8.1
found to be an efficientcatalyst for the one-pot esterification and deprotection of (5S,6R)-5,6-diacetoxyoct-7-enoic acid in good yields (44−62%) with a lactone formed as a minor byproduct. ZrCl4 (10−20 mol %) was also sufficient to deprotect 1,3-dioxalane, bis-TBDMS ethers, and diacetate functional groups in excellent yields of up to 93%. ZrCl4 (1−10 mol %) also promoted diol protection as the acetonide