Concise Enantiospecific, Stereoselective Syntheses of (+)-Crispine A and Its (−)-Antipode
摘要:
An enantiospecific and stereoselective total synthesis of the natural product (+)-crispine A has been demonstrated employing a Pictet-Spengler bis-cyclization reaction between commercially available (R)-(-)-methyl 2-amino-3-(3,4-dimethoxyphenyl)propanoate and 4-chloro-1,1-dimethoxybutane to preferentially provide the cis tricyclic adduct. Decarboxylation by a convenient two-step protocol provided the enantiopure natural product in three steps with an overall isolated yield of 32% from the amino acid. The unnatural antipode (-)-crispine A was similarly prepared in three steps from the commercially available (S)-(+)-amino acid.
Enantioselective synthesis of non-proteinogenic amino acids via metallated bis-lactim ethers of 2,5-diketopiperazines
作者:Ulrich Schöllkopf
DOI:10.1016/s0040-4020(01)91926-x
日期:1983.1
excess = asymmetric induction) of the adduct exceeds 95%. On hydrolysis the adducts are cleaved liberating the chiral auxiliary (used to build up the bis-lactim ether 1) and the target molecules, the opticallyactive amino acid methyl esters of type 8,19,25 or 36. The two amino acid esters are separable either by fractional distillation or (eventually after further hydrolysis to amino acids) by chromatography
the sub‐100 nM range, with high selectivity over inhibition of the endocannabinoid‐degrading enzyme fatty acid amide hydrolase; two compounds were virtually equipotent with 1. Interestingly, profound activity differences were observed between analogues in which either of the two methoxy substituents in the head group had been replaced by the same bulkier alkoxy group. Some of the compounds described here
New Synthetic Amino Acids for the Design and Synthesis of Peptide-Based Metal Ion Sensors
作者:Alicia Torrado、Barbara Imperiali
DOI:10.1021/jo961466w
日期:1996.1.1
The syntheses of two new nonstandard amino acids, Flu (6) and YBp (20), and a new synthesis of Dmd (12) are reported. These residues exhibit fluorescence, metal-coordination, and fluorescence-quenching properties, respectively. These building blocks have been incorporated into peptides via solid phase peptide synthesis to afford the prototype fur a photoinduced electron transfer-based metal ion chemosensor. The fluorescence of the peptides is modulated upon metal binding. This results from a metal. ion-induced conformational change that brings the side chains of the Flu and Dmd amino acids into proximity, thereby favoring photoinduced electron transfer (PET) fluorescence quenching.
Short stereoselective synthesis of (+)-crispine A via an N-sulfinyl Pictet–Spengler reaction
作者:Rubén Sánchez-Obregón、Benjamín Ortiz、Virginia M. Mastranzo、Francisco Yuste、José Luis García Ruano
DOI:10.1016/j.tetlet.2013.01.121
日期:2013.4
We report the highly stereoselective synthesis of (R)-(+)-crispine A from the (R)-N-sulfinyl amine 1 by using a one-pot process involving the Pictet-Spengler reaction with 4-chlorobutanal, removal of the sulfinyl group by protonolysis of the N-S bond and in situ cyclization, with a 55% overall yield. (C) 2013 Elsevier Ltd. All rights reserved.