Convolutamydine A: the first authenticated absolute configuration and enantioselective synthesis
摘要:
The absolute configuration of (+)-convolutamydine A 1 isolated from Amathia convoluta has been unambiguously established as (R) by enantioselective synthesis, based on chiral auxiliary-directed pi-face discrimination in an allyl metal addition to (1R,2S,5R)-8-phenylmenthyl ester 7. For an independent and unequivocal proof, the absolute stereochemistry of synthetic precursor 11 en route to 1 was determined by X-ray crystallography. (c) 2006 Published by Elsevier Ltd.
l-proline-derived bifunctional organocatalyst. This strategy allows the enantioselective synthesis of a variety of 3-alkyl-3-hydroxyindolin-2-ones with a stereogenic quaternary carbon center in excellent yields with good to excellent enantiomeric excess. The method has been applied to the enatioselective synthesis of (S)-convolutamydine A successfully.
Vicinal Amino Alcohols as Organocatalysts in Asymmetric Cross-Aldol Reaction of Ketones: Application in the Synthesis of Convolutamydine A
作者:Andrei V. Malkov、Mikhail A. Kabeshov、Marco Bella、Ondřej Kysilka、Denis A. Malyshev、Kristýna Pluháčková、Pavel Kočovský
DOI:10.1021/ol7023983
日期:2007.12.1
Leucinol and valinol have been identified as efficient organocatalysts for the aldol reaction of isatin and its derivatives (as examples of activated, non-enolizable ketones) with acetone. Uncommon mechanistic features were observed and used in the formulation of the transition state of the reaction.
N‐(2‐Thiophenesulfonyl)prolinamide could be easily introduced into Montmorillonite by a simple ion‐exchange reaction. The asymmetric aldolreactions between various isatins with acetone or acetaldehyde using a heterogeneous Montmorillonite‐entrapped organocatalyst afforded products with high enantioselectivity. The catalyst was readily reusable without significant loss of catalytic activity or enantioselectivity.
A DFT and AIM Study of the Proline-Catalyzed Asymmetric Cross-Aldol Addition of Acetone to Isatins: A Rationalization for the Reversal of Chirality
作者:Rodrigo J. Corrêa、Simon J. Garden、Gaetano Angelici、Claudia Tomasini
DOI:10.1002/ejoc.200700944
日期:2008.2
effects that control the enantioselectivity in the cross-aldol addition of acetone to isatincatalyzed by L-proline have been studied by means of DFT and AIM calculations. This reaction results in a reversal of enantioselectivity compared with the corresponding cross-aldol addition to 4,6-dibromoisatin and aldehydes. DFT calculations of the cross-aldol transition states indicate that product formation
已经通过 DFT 和 AIM 计算研究了空间和立体电子效应,这些效应控制在 L-脯氨酸催化下丙酮与靛红的交叉羟醛加成中的对映选择性。与相应的交叉羟醛添加到 4,6-二溴靛红和醛相比,该反应导致对映选择性的逆转。跨羟醛过渡态的 DFT 计算表明,对于底物靛红和 4,6-二溴靛红,产物的形成遵循不同的途径。在靛红的情况下,由于立体电子效应导致 S 对映体相对于 R 对映体具有较低能量的过渡态,因此 S 对映体受到青睐。相比之下,丙酮与 4 的交叉羟醛加成,
The first total synthesis of (R)-convolutamydine A
作者:Gianluigi Luppi、Magda Monari、Rodrigo J. Corrêa、Flavio de A. Violante、Angelo C. Pinto、Bernard Kaptein、Quirinus B. Broxterman、Simon J. Garden、Claudia Tomasini
DOI:10.1016/j.tet.2006.09.077
日期:2006.12
The firsttotalsynthesis of (R)-convolutamydine A has been achieved by the organocatalytic addition of acetone to 4,6-dibromoisatin. The absolute configuration was determined by single crystal X-ray diffraction. DFT studies were used to model the transition states for the aldol reaction and equilibrium geometries of the post-aldol reaction intermediates. The DFT study revealed that the aldol bond