Y. Takagi, O. Kawashima, T. Tsuchiya
Nov 1, 1976
Citations
0
Influential Citations
3
Citations
Journal
Bulletin of the Chemical Society of Japan
Abstract
Reactions of 2-guanidino-1-cyclohexanols (1, 1d, 1l) with 1,1-dimethoxycyclohexane in N,N-dimethylformamide in the presence of p-toluenesulfonic acid gave the N,O-cyclohexylidene derivatives (5, 5d, 5l), respectively. Similar reactions of 1l with 2,2-dimethoxypropane and with dimethyl acetals of p-tolualdehyde and p-bromobenzaldehyde also gave an N,O-isopropylindene, N,O-(p-methylbenzylidene) and N,O-(p-brornobenzylidene) derivative (8l, 9l, 10l), respectively. From IR and PMR spectral studies of 9l p-toluenesulfonate, seven-membered structures as exemplified by 9A were assigned. The N,O-blocked derivatives (5,9) are stable in weakly acidic or alkaline media, but in stronger media, they are cleaved to 1. The usefulness of the protective groups was also examined. 9 was found to resist tosylation or mesylation in pyridine but not acylation. The numerical values of optical rotations of the guanidinocyclohexanols were greatly enhanced by N, O-blocking.