Intramolecular formal [4+2] cycloadditionbetween 3-ethoxycyclobutanones and a carbon-carbon double bond to the corresponding bicyclo[4.n.0]alkan-2-one derivatives proceeded effectively by using ethylaluminium dichloride.
Trialkylamine-mediated intramolecular cyclization of pent-4-enoyl chlorides was studied. Substitution with a tertiary alkyl group at the 2-position gave cyclopent-2-en-1-ones, while substitution with an aromatic group gave enol esters, which were formed by O-acylation of initially formed 3-chlorocyclopentanones with ketenes.
SAR of 2-benzyl-4-aminopiperidines NK1 antagonists. Part 21. synthesis of CGP 49823
作者:Siem J. Veenstra、Kathleen Hauser、Walter Schilling、Claudia Betschart、Silvio Ofner
DOI:10.1016/s0960-894x(96)00563-x
日期:1996.12
CGP 49823 is a potent NK1 antagonist which is centrally active after oral administration. The SAR of the C-2 substituent was investigated with respect to the affinity to the NK1 receptor. A practical synthesis of CGP 49823, suitable for scale-up, was developed. The key-step, a tandem acyliminium ion cyclization / Ritter reaction, gave trans 2-benzyl-4-acetamido-piperidines with high diastereoselectivity. Copyright (C) 1996 Elsevier Science Ltd
Stereochemistry in enzyme inhibition: synthesis and evaluation of enantiomerically pure 2-benzyl-3-formylpropanoic acids as inhibitors of carboxypeptidase A
作者:Dong H. Kim、Suhman Chung
DOI:10.1016/s0957-4166(99)00421-8
日期:1999.9
Both enantiomers of 2-benzyl-3-formylpropanoic acid were synthesized in five steps starting with hydrocinnamic acid and each enantiomer assayed for inhibitory activity against carboxypeptidase A to find that the (R)-form is 674-fold more potent than its enantiomer. The finding that the (R)-form which belongs to the L-series is mostly responsible for the inhibitory activity accords with the explanation that the present inhibitor is a transition state analog inhibitor because, as such, its stereochemistry should belong to the same series as that of the substrate, i.e., the L-series. The gem-diol form of the inhibitor generated in situ mimics the transition state in the catalytic process.