A general method for the facile synthesis of optically active 2-substituted piperazines via functionalized 2,5-diketopiperazines
作者:Kate S. Ashton、Mitchell Denti、Mark H. Norman、David J. St. Jean
DOI:10.1016/j.tetlet.2014.06.058
日期:2014.8
Upon utilization of some common methods described in the literature for the synthesis of chiral, 2-substituted 2,5-diketopiperazines, extensive racemization was observed. Further investigation showed that heating in the presence of a mild base racemized the chiral center in the product diketopiperazines. A generalized, readily scalable route was sought and, after investigating the effect of base and
Penicillin acylase-catalyzed peptide synthesis in aqueous medium: a chemo-enzymatic route to stereoisomerically pure diketopiperazines
作者:Andrei Y. Khimiuk、Alexei V. Korennykh、Luuk M. van Langen、Fred van Rantwijk、Roger A. Sheldon、Vytas K. Švedas
DOI:10.1016/j.tetasy.2003.08.011
日期:2003.10
corresponding amino acids. The conversion of the dipeptides to the corresponding dipeptide esters, followed by their subsequent spontaneous cyclization afforded the corresponding stereoisomerically purediketopiperazines.
Triisobutylaluminium-Mediated Regioselective Protection of Sterically Hindered Amide NH of Cyclo-(AA-Gly): Key Building Block for Next-Generation Peptide Synthesis
regioselective Boc protection in the more stericallyhindered amide NH of unsymmetrical 2,5-diketopiperazines (DKPs) formed from glycine and various amino acids. Our research introduces a novel technique utilizing cost-effective triisobutylaluminium and trimethoxysilane. Notably, trimethoxysilane selectively reacts with the less hindered amide NH, facilitating the regioselective Boc protection of the
A solvent in which dichloromethane is mixed with alcohol as a poor solvent is used for preparing a dope. Alcohol is supplied to the dope in a inline pipe to mix with a static mixer, such as a casting dope in which a composition of alcohol is increased. The temperature of the rotary drum is adjusted to −7° C. The casting dope is fed from a casting die to the rotary drum so as to form a casting film whose thickness is 40 μm. Since the content of alcohol is high and a storage modulus of the cooled casting film is at least 150 thousands Pa, the peeling defect does not occur, and the stretch is reduced as far as possible. A gel-like film is dried by a tenter type drying device, and stretched such that the stretch ratio is at most 110%. The produced film is thin and excellent in a surface condition and optical isotropy.