A Facile Method for Preparation of Novel Cyclopropanespirohydantoins

Abstract

A facile synthetic approach to 3'-substituted-5-cyclopropanespirohydantoins has been developed and used to synthesize some new spirohydantoins. The key aspect is the preparation of -carboethoxy isocyanate basing on Curtius rearrangement, which can be ring-closed to the expected spirohydantoins after the reaction with various amines and hydrazines. Interestingly the cyclopropane ring doesn't open during the whole process.

A new synthesis of 3-arylideneamino- and 3-alkylideneamino-substituted hydantoins

“…1 H NMR spectrum of the latter in DMSO-d6 showed three singlet signals at 10.26, 9.81, and 5.01 ppm with relative intensities of 1:1:2, which can be assigned respectively to the NH, CH=N, and NH2 protons in enamine 4a. The structure of this compound was also confirmed by its 13 C NMR spectrum and DFT computational data (see below). Thus, this synthesis afforded a mixture of 2a and 4a in a ratio of 85:15.…”

“…Thus, it can be assumed that these stereoisomers are in dynamic equilibrium in DMSO. Apparently, some deviation of the calculated and experimental chemical shifts in the 13 C-NMR spectrum of compound 4a (see above) can be explained by this equilibrium.…”

“…However, in contrast to 1-aminohydantoins, their 3-amino analogues are much less studied. Described syntheses of 3-aminohydantoin derivatives from acyclic precursors generally involve formation of one or two C-N bonds (e.g., N3-C4 [8,[12][13][14][15], C2-N3 [16][17][18], both N1-C2 and N3-C4 [19][20][21][22][23], both N1-C5 and N3-C4 bonds [24]). These compounds are also prepared using recyclizations of certain heterocyclic compounds [25][26][27][28][29][30][31][32][33].…”