prepared, respectively, and the preferredconformations of cyclohexane rings of amino acid residues and the peptide-backbones were studied. In solution, these peptides formed helical structures, but the helical-screw control to one-handedness was not possible for the hexapeptide length. In the crystal state, all (1R,3R)-Ac6c3M residues formed cyclohexane chair form conformations with a 3-methyl substituent
两个非对映体的六元环α,α-二取代的α-氨基酸(1 R,3 R)-和(1 S,3 R)-1-氨基-3-甲基环己烷羧酸(Ac 6 c 3M);侧链限制性亮氨酸类似物,是通过Bucherer-Bergs或Strecker反应从(3 R)-3-甲基环己酮立体选择性合成的。两个系列的同手性同型肽Cbz-[(1R,3 R)-和(1S,3 R)-Ac 6 c 3M ] n -OMe,直至六肽(n分别制备== 6),并研究了氨基酸残基的环己烷环和肽链的优选构象。在溶液中,这些肽形成了螺旋结构,但是对于六肽长度,不可能将螺旋螺钉控制为单手。在晶体状态下,所有(1 R,3 R)-Ac 6 c 3M残基形成环己烷椅,在赤道方向上带有3-甲基取代基,在轴向上带有氨基,而所有(1 S,3 R)-Ac 6 c 3M假定环己烷椅子形式的残基具有在赤道取向的3-甲基和氨基。(1 R,3 R)-Ac 6 c 3M六肽的优选肽骨干结构具有(P)和(M)3
Microwave-assisted synthesis of cycloalkanespirohydantoins and piperidylspirohydantoins as precursors of restricted α-amino acids
作者:Ignacio A. Rivero、Edgar A. Reynoso、Adrian Ochoa-Teran
DOI:10.3998/ark.5550190.0012.221
日期:——
Cycloalkanespirohydantoins 3 and piperidinespirohydantoins 4 were synthesized from cycloalkanones 9 and piperidones 10 under microwave-assisted conditions. Results are compared with those obtained under thermal conditions. Cycloalkanespirohydantoins 3 were N-protected with Boc group and hydrolyzed under basic conditions to obtain five, six and seven-membered ring restrictedα-aminoacids 12 in very