Bifunctional amidoiridium

Chiral epoxides from racemic haloalcohols were efficiently synthesized via a DKR process. The enzyme haloalcohol dehydrogenase was used for the KR of p-haloalcohols to give the enantioenriched epoxide, and the slow reacting enantiomer was racemized with an iridium complex furnishing epoxides in excellent yield and high ee (98%) (Scheme 4.31) [81]. Similarly, several chiral acetates were obtained from racemic secondary alcohols in excellent yields with high enantioselectivities through the use of CALB with bifunctional amidoiridium complexes derived from benzylic amines [82],... 

In 2012, Ikariya et al. found that a combined catalyst system of bifunctional amidoiridium complexes derived from benzylic amines with lipase CALB could provide a range of chiral acetates from racemic secondary alcohols through DKR with nearly perfect enantioselectivities, as shown in Scheme 8.65. ° ... 

Scheme 8.65 Enzymatic DKR of alcohols with a bifunctional amidoiridium complex.

Chiral N-sulfonyldiamine ligands are used to create effective chiral bifunctional amidoiridium catalysts for the asymmetric aerobic oxidation of meso- and prochiral diols to give up to >99% ee of hydroxyl ketones and 50%ee oflactones. " These catalysts can be also applied for an efficient oxidative kinetic resolution of racemic secondary alcohols affording R enantiomers with >99% ee and with 46—50% yields. 

Suzuki T, Morita K, Matsuo Y, Hiroi K. Catalytic asymmetric oxidative lactonizations of meso-diols using a chiral iridium complex. Tetrahedron Lett. 2003 44 2003—2006. Moritani J, Hasegawa Y, Kayaki Y, Ikariya T. Aerobic oxidative desymmetrization of meso-diols with bifunctional amidoiridium catalysts bearing chiral N-sulfonyldiamine ligands. Tetrahedron Lett. 2014 55 1188-1191. 

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