invertive B-alkyl Suzuki-Miyaura coupling has been achieved. The coupling of enantioenriched α-(acylamino)benzylboronic esters with aryl bromides and chlorides took place efficiently in toluene at 80 °C in the presence of Pd(dba)(2) (5 mol %), XPhos (10 mol %), K(2)CO(3) (3 equiv), and H(2)O (2 equiv). The reaction proceeded with inversion of configuration to give diarylmethanamine derivatives in high
Inversion or Retention? Effects of Acidic Additives on the Stereochemical Course in Enantiospecific Suzuki–Miyaura Coupling of α-(Acetylamino)benzylboronic Esters
The stereochemicalcourse of the stereospecific Suzuki-Miyaura coupling of enantioenriched α-(acetylamino)benzylboronic esters with aryl bromides can be switched by the choice of acidic additives in the presence of a Pd/XPhos catalyst system. Highly enantiospecific, invertive C-C bond formation takes place with the use of phenol as an additive. In contrast, high enantiospecificity for retention of
在 Pd/XPhos 催化剂体系的存在下,可以通过选择酸性添加剂来切换对映体富集的 α-(乙酰氨基)苄基硼酸酯与芳基溴的立体定向 Suzuki-Miyaura 偶联的立体化学过程。使用苯酚作为添加剂可形成高度对映体的、倒置 CC 键。相比之下,在 Zr(Oi-Pr)(4)·i-PrOH 作为添加剂存在的情况下,实现了构型保留的高对映特异性。
Bis-Sulfamyl Imines: Potent Substrates for Asymmetric Additions of Arylboroxines under Rhodium Catalysis
作者:Rosemary Crampton、Simon Woodward、Martin Fox
DOI:10.1002/adsc.201000838
日期:2011.4.18
Bis‐sulfamyl imines are shown to be potentially ideal substrates for rhodium‐catalysed asymmetricadditions of arylboron nucleophiles as they show: (i) near perfect enantioselectivities (11 examples, 98–99+% ee), (ii) good to excellent diastereoselectivities (10–32:1 rac:meso), and (iii) high functional group tolerance in removal of the low molecular weight protecting group via mild heating in aqueous
作者:Guohua Hou、Francis Gosselin、Wei Li、J. Christopher McWilliams、Yongkui Sun、Mark Weisel、Paul D. O’Shea、Cheng-yi Chen、Ian W. Davies、Xumu Zhang
DOI:10.1021/ja903319r
日期:2009.7.29
N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitrites and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v using Ir-(S,S)-f binaphane as catalyst provides chiral amines 4a-4v in 90-95% yield with enantioselectivities up to 95% ee.
Iridium−Monodentate Phosphoramidite-Catalyzed Asymmetric Hydrogenation of Substituted Benzophenone N−H Imines
Homogeneous asymmetric hydrogenation of unprotected benzophenone N-H imines 1a-r using 1r-benzyl-N-methyl-MonoPhos as a catalyst provides chiral amines 2a-r in 80-96% yield with enantioselectivities up to 98% ee (18 examples) for ortho-substituted substrates.