Chiral [2.2.2] Dienes as Ligands for Rh(I) in Conjugate Additions of Boronic Acids to a Wide Range of Acceptors
作者:Christian Defieber、Jean-François Paquin、Sonia Serna、Erick M. Carreira
DOI:10.1021/ol048240x
日期:2004.10.1
[reaction: see text] We document a series of investigations that led to new substituted [2.2.2]-diene ligands which display high selectivity in Rh(I)-catalyzed conjugate addition reactions to substrates not previously examined with diene ligands. Moreover, we disclose an unexpected, interesting effect that results from the introduction of a third C=C onto the ligand scaffold (cf. 1).
For the first time the room-temperature rhodium-catalyzedasymmetric1,4-addition of potassium aryltrifluoroborates to α,β-unsaturated substrates is described. Thanks to the use of a chiral diene as ligand for rhodium and triethylamine as base, to facilitate transmetalation of the boron species, high yields and enantioselectivities were generally achieved. Moreover, the use of such tetravalent boron
Application of chiral tetrahydropentalene ligands in rhodium-catalyzed 1,4-addition of (E)-2-phenylethenyl- and (Z)-propenylboronic acids to enones
作者:Sarah Helbig、Kirill V. Axenov、Stefan Tussetschläger、Wolfgang Frey、Sabine Laschat
DOI:10.1016/j.tetlet.2012.04.130
日期:2012.7
6aR)-1 have been prepared and used as ligands in the Rh-catalyzed 1,4-addition of 1-alkenylboronic acids to cyclic enones 5. It has been discovered that the stereochemistry of the reaction was controlled by the steric properties of the aryl groups in 1 rather than their electronic nature. In the vinylation with (E)-2-phenylethenylboronic acid 5, ligands (3aR,6aR)-1 provided enantioselectivity up to 87%
Rhodium-catalyzed asymmetric 1,4-addition of alkenylsilanes generated by hydrosilylation of alkynes: a one-pot procedure where a rhodium/(S)-binap complex catalyzes the two successive reactions
作者:Yusuke Otomaru、Tamio Hayashi
DOI:10.1016/j.tetasy.2004.07.003
日期:2004.9
A rhodium complex [Rh((S)-binap)(MeCN)(2)]BF4 (3mol%) catalyzes successively hydrosilylation of 1-alkynes with triethoxysilane and asymmetric 1,4-addition of the resulting alkenylsilanes to cyclic alpha,beta-unsaturated ketones. This one-pot procedure gave high yield of the corresponding 1,4-addition products with over 90% enantioselectivity. (C) 2004 Elsevier Ltd. All rights reserved.
Highly Enantioselective Alkenylation of Cyclic α,β-Unsaturated Carbonyl Compounds as Catalyzed by a Rhodium-Diene Complex: Application to the Synthesis of (<i>S</i>)-Pregabalin and (−)-α-Kainic Acid
作者:Hong-Jie Yu、Cheng Shao、Zhe Cui、Chen-Guo Feng、Guo-Qiang Lin
DOI:10.1002/chem.201202660
日期:2012.10.15
Rhod to addition: An efficient asymmetric conjugate‐addition reaction of alkenyltrifluoroborates and α,β‐unsaturated carbonyl compounds, as catalyzed by a rhodium–dienecomplex, was developed. The products were obtained in high yield and high levels of enantioselectivity. The methodology was applied to a concise synthesis of (S)‐pregabalin and (−)‐α‐kainic acid (see scheme).