of C10-BridgePHOS oxides possessing different substituted groups on the diphenyl phosphine system were synthesized and tested as organocatalysts in the allylation of aldehydes with allyltrichlorosilane, providing chiral homoallylic alcohols. These types of organocatalysts showed high catalytic activity and only 2 mol% catalyst loading was required to induce short reaction times. Under optimal reaction
Bimetallic catalysis: The first palladium catalysts capable of controlling asymmetric nucleophilic allylations of aldehydes with allyltributyltin are reported. Unprecedented TONs for this reaction type were achieved (up to 620). The method is also tolerating electronically and sterically unfavorable substrates. A transmetallation occurs, favoring an η1-allyl coordination mode with the reported bispalladacycle
双金属催化:报道了第一个能够控制醛与烯丙基三丁基锡的不对称亲核烯丙基化的钯催化剂。这种反应类型的 TON 达到了前所未有的水平(高达 620)。该方法还可以容忍电子和空间上不利的底物。发生金属转移,有利于 η 1 -烯丙基配位模式与报道的双钯环催化剂,而对于相应的单钯环催化剂,非生产性的 η 3 -配位占主导地位。
Enantioselective Iridium-Catalyzed Carbonyl Allylation from the Alcohol or Aldehyde Oxidation Level via Transfer Hydrogenative Coupling of Allyl Acetate: Departure from Chirally Modified Allyl Metal Reagents in Carbonyl Addition
作者:In Su Kim、Ming-Yu Ngai、Michael J. Krische
DOI:10.1021/ja805722e
日期:2008.11.5
Under the conditions of transferhydrogenationemploying an iridium catalyst generated in situ from [Ir(cod)Cl]2, chiral phosphine ligand (R)-BINAP or (R)-Cl,MeO-BIPHEP, and m-nitrobenzoic acid, allyl acetate couples to allylic alcohols 1a-c, aliphatic alcohols 1d-l, and benzylic alcohols 1m-u to furnish products of carbonyl allylation 3a-u with exceptional levels of asymmetric induction. The very
Enantioselective Iridium-Catalyzed Carbonyl Allylation from the Alcohol or Aldehyde Oxidation Level Using Allyl Acetate as an Allyl Metal Surrogate
作者:In Su Kim、Ming-Yu Ngai、Michael J. Krische
DOI:10.1021/ja802001b
日期:2008.5.1
enantioselective carbonyl allylation from the alcohol or aldehyde oxidation level are described based upon transfer hydrogenative C-C coupling. Exposure of allyl acetate to benzylic alcohols 1a-i in the presence of an iridium catalyst derived from [IrCl(cod)]2 and (R)-BINAP delivers products of C-allylation 2a-i. Employing isopropanol as terminal reductant, exposure of allyl acetate to aryl aldehydes