Synthesis and evaluation of guanidinyl pyrrolidines as bifunctional catalysts for enantioselective conjugate additions to cyclic enones
作者:Sunil V. Pansare、Rajinikanth Lingampally
DOI:10.1039/b812038b
日期:——
Guanidinyl pyrrolidines derived from ‘S’-proline are effective catalysts for the enantioselective conjugate addition of malonate, nitroalkane and other carbon and heteroatom nucleophiles to cyclohexenone and cyclopentenone in the absence of basic additives. The stereoselectivity is strongly dependant on catalyst loading as well as reaction concentration.
衍生自“ S ”-脯氨酸的胍基吡咯烷是将丙二酸酯,硝基烷和其他碳原子和杂原子亲核试剂对映选择性共轭加成的有效催化剂。环己烯酮 和 环戊烯酮在没有碱性添加剂的情况下。立体选择性很大程度上取决于催化剂的负载以及反应浓度。
Enantioselective total synthesis of (−)-strychnine: development of a highly practical catalytic asymmetric carbon–carbon bond formation and domino cyclization
An enantioselective totalsynthesis of (−)-strychnine was accomplished through the use of the highly practical catalyticasymmetricMichaelreaction (0.1 mol% of (R)-ALB, greater than kilogram scale, without chromatography, 91% yield and >99% ee), and a domino cyclization that simultaneously constructed the B- and D- rings of strychnine (>77% yield). Newly-developed reaction conditions for thionium
Asymmetric Michael Addition of Malonates to Enones Catalyzed by a Primary β-Amino Acid and Its Lithium Salt
作者:Masanori Yoshida、Mao Narita、Shoji Hara
DOI:10.1021/jo201429w
日期:2011.10.21
Highly enantioselective Michaeladdition of malonates to enones was achieved using a mixed catalyst consisting of a primary β-amino acid, O-TBDPS (S)-β-homoserine, and its lithium salt. Various cyclic and acyclic enones were converted into 1,5-ketoesters in high yields (up to 92%) with high enantioselectivity (up to 97% ee) under mild reaction conditions. Details of synthesis of the catalyst, optimization
a new lithium-free BINOL-lanthanum complex, which is quite effective in catalyticasymmetricMichaelreaction. We have succeeded in developing effective asymmetric base catalysts, in particular, asymmetric ester enolate catalysts for asymmetricMichaelreactions. Two asymmetric lanthanum complexes are now available, namely, BINOL-lanthanum-lithium complex, which is quite effective in catalytic asymmetric
Asymmetric organocatalytic conjugate addition of malonates to enones using a proline tetrazole catalyst
作者:Kristian Rahbek Knudsen、Claire E. T. Mitchell、Steven V. Ley
DOI:10.1039/b514636d
日期:——
5-Pyrrolidin-2-yltetrazole performs as a useful organocatalyst for the asymmetric addition of malonates to a range of enones, with good to excellent enantioselectivities.