Direct and Highly Enantioselective Iso-Pictet–Spengler Reactions with α-Ketoamides: Access to Underexplored Indole Core Structures
摘要:
Direct, one-pot, operationally simple, and highly enantioselective iso-Pictet-Spengler reactions are reported. The reactions involve the condensation of either (1H-indol-4-yl)methanamine or 2-(1H-Indol-1-yl)ethanamine with a variety of alpha-ketoamides, followed by the addition of a simple and commercially available chiral silicon Lewis acid. These reactions are the first asymmetric examples of these cyclization modes and provide access to 3,3-disubstituted-1,3,4,5-tetrahydropyrrolo[4,3,2-de]isoquinolines and 1,1-disubstituted-1,2,3,4-tetrahydropyrazino[1,2-a]indoles, respectively, two relatively underexplored indole-based core structure motifs in medicinal chemistry.
Air-sensitive, thermally unstable tris(dimethylamino)sulfonium (TAS) salts (3) of the title anions [ArNSN](-) have been prepared from corresponding sulfurdiimides Ar-N=S=N-SiMe3 (2) by Si-N bond cleavage with [(Me2N)(3)S](+)[Me3SiF2](-)(TASF). They are characterized by low-temperature X-ray crystallography as Z isomers. Because of the very short terminal S-NI distance (144.2 (3h) - 147.9 (3i) pm) and the relatively long internal S-N distance (158.3 (3i) - 160.3 (3c) pm) the [ArNSN](-) ions should be regarded as thiazylamides 1b, rare species containing a SN triple bond. A bonding model is developed and the experimental results are compared with those of restricted Hartree-Fock (R drop HF), density functional theory (DFT), and Moller-Plesset second-order (MP2) calculations.
Miller, A. O.; Zibarev, A. V.; Fedotov, M. A., Journal of general chemistry of the USSR, 1989, vol. 59, # 31, p. 518 - 521
作者:Miller, A. O.、Zibarev, A. V.、Fedotov, M. A.、Furin, G. G.
DOI:——
日期:——
MILLER, A. O.;ZIBAREV, A. V.;FEDOTOV, M. A.;FURIN, G. G., ZH. OBSHCH. XIMII, 59,(1989) N, S. 586-590
作者:MILLER, A. O.、ZIBAREV, A. V.、FEDOTOV, M. A.、FURIN, G. G.
DOI:——
日期:——
ZIBAREV, ANDREY V.;MILLER, ALEXEY O.;GATILOV, YURI V.;FURIN, GEORGII G., HETEROATOM CHEM., 1,(1990) N, C. 443-453
作者:ZIBAREV, ANDREY V.、MILLER, ALEXEY O.、GATILOV, YURI V.、FURIN, GEORGII G.
DOI:——
日期:——
Highly Enantioselective Pictet-Spengler Reactions with α-Ketoamide-Derived Ketimines: Access to an Unusual Class of Quaternary α-Amino Amides
作者:Farhan R. Bou-Hamdan、James L. Leighton
DOI:10.1002/anie.200806110
日期:2009.3.16
story? N‐Aryl amides are effective directing/activating groups for chlorosilane Lewis acids. This aspect has been exploited for the development of the first simple and general method for the highlyenantioselective Pictet–Spengler reaction of ketimines derived from α‐ketoamides leading to quaternary α‐aminoacid derivatives (see scheme).