Separation of pyrrolidine allylation products by diastereoselective enzymatic ester hydrolysis

Stereocontrolled Synthesis of Phosphoproline Analogues Containing a trans-Fused Octahydroindole Bicyclic System

Herein we report for the first time the diastereoselective synthesis of (2R,3aR,7aS)- and (2S,3aS,7aR)-octahydroindole-2-phosphonic acid (OicP trans-fused stereoisomers) from diethyl (R)- and (S)-phosphopyroglutamate derivative. The key steps of this procedure are the ruthenium tetroxide oxidation of enantiomerically pure diethyl (R)- and (S)-phosphoprolinate obtained through Katritzky's benzotriazole-oxazolidine methodology, a highly diastereoselective successive double 4,5-diallylation of diethyl (R)- and (S)-phosphopyroglutamate with allyl bromide and allyltrimethylsilane with a trans-addition mode, and a ring-closing metathesis with Grubbs' first-generation ruthenium catalyst.

Current applications of kinetic resolution in the asymmetric synthesis of substituted pyrrolidines

Chiral substituted pyrrolidines are key elements in various biologically active molecules and are therefore valuable synthetic targets. One traditional method towards enantiomerically pure compounds is the application of kinetic resolution. In this review, current KR methodology used in the synthesis of substituted pyrrolidines is surveyed, including enzymatic methods, cycloadditions and reduction of ketones.

Synthesis of Conformationally Constrained Dipeptide Mimetics with Azabicyclo[4,3,0]nonanone and Azabicyclo[5,3,0]decanone Scaffolds

A general and efficient method for the synthesis of azabicyclo[4,3,0]nonanone and azabicyclo[5,3,0]decanone amino acid derivatives was developed with the palladium-catalyzed coupling of intermediates 9 and 10 with BocNH₂ and Boc₂NH and the following reduction of the C-C double bond by hydrogenation as the key steps. The exploration of the synthesis of C₆-substituted dipeptide mimetics from 9 and 10 using Suzuki coupling as the key reaction has also been performed.

Chemical characterization of constituents from Polygonatum cyrtonema Hua and their cytotoxic and antioxidant evaluation

Twenty-four compounds were isolated from the roots of Polygonatum cyrtonema Hua, including a new octopamine dimer, named trans-bis(N-feruloyl)octopamine (1). The structure was established on the basis of spectroscopic and chemical methods. All the extracts and compounds were evaluated for cytotoxic and antioxidant activities by using MTT and chemiluminescence assay. The extracts showed activity against MCF-7 and HepG-2 cell lines from IC₅₀ 0.30 to 1.01 mg mL^-1. Compound 3 exhibited activity against HepG-2 cell lines with IC₅₀ 8.99 μM. Compound 7 exhibited activity against Hela cell lines with IC₅₀ 2.53 μM and BGC-823 cell lines with IC₅₀ 7.77 μM. Moreover, compound 7 showed antioxidant with IC₅₀ 12 µM compared to the positive control with IC₅₀ 77 µM. Compound 16 exhibited activity against HepG-2 cell lines with IC₅₀ 1.05 μM and MCF-7 cell lines with IC₅₀ 1.89 μM. These results indicated that this plant might be potential in natural medicine and healthy food.