Efficient synthesis of biologically important chiral 2-alkylamino benzoxazinones
摘要:
A novel general method has been developed for the synthesis of various amino acid derived chiral 2-substituted benzoxazinones, known inhibitors of standard serine proteases of the chymotrypsin superfamily. (C) 1997 Elsevier Science Ltd.
First Total Synthesis of (-)-Circumdatin H, a Novel Mitochondrial NADH Oxidase Inhibitor
作者:D. Bose、M. Chary
DOI:10.1055/s-0029-1218606
日期:2010.2
convergent synthesis of the mitochondrial NADH oxidase inhibitor (-)-circumdatin H is described. The strategy employs the intramolecular Eguchi aza-Wittig protocol as a key step to install the crucial central core BC ring system, leading to the firsttotalsynthesis of the target molecule. benzodiazepine alkaloids - circumdatin H - mitochondrial NADH oxidase - intramolecular aza-Wittig reaction - Eguchi
Sequence-Specific Unusual (1→2)-Type Helical Turns in α/β-Hybrid Peptides
作者:Panchami Prabhakaran、Sangram S. Kale、Vedavati G. Puranik、P. R. Rajamohanan、Olga Chetina、Judith A. K. Howard、Hans-Jörg Hofmann、Gangadhar J. Sanjayan
DOI:10.1021/ja804297f
日期:2008.12.31
This article describes novel conformationally ordered (alpha/beta-hybrid peptides consisting of repeating L-proline-anthranilic acid building blocks. These oligomers adopt a compact, right-handed helical architecture determined by the intrinsic conformational preferences of the individual amino acid residues. The striking feature of these oligomers is their ability to display an unusual periodic pseudo beta-turn network of nine-membered hydrogen-bonded rings formed in the forward direction of the sequence by 1-->2 amino acid interactions both in solid-state and in solution. Conformational investigations of several of these oligomers by single-crystal X-ray diffraction, solution-state NMR, and ab initio MO theory suggest that the characteristic steric and dihedral angle restraints exerted by proline are essential for stabilizing the unusual pseudo beta-turn network found in these oligomers. Replacing proline by the conformationally flexible analogue alanine (Ala) or by the conformationally more constrained alpha-amino isobutyric acid (Aib) had an adverse effect on the stabilization of this structural architecture. These findings increase the potential to design novel secondary structure elements profiting from the steric and dihedral angle constraints of the amino acid constituents and help to augment the conformational space available for synthetic oligomer design with diverse backbone structures.