Light-Sensitive Protecting Groups for Amines and Alcohols: The Photosolvolysis of N-Substituted 7-Nitroindolines

Abstract

Representative examples of primary and secondary amines were protected as urea derivatives 4 of 5-bromo-7-nitro­indoline and even more efficiently as ureas 8 derived from 5,7-di­nitroindoline, via high-yield reactions with carbamoyl chlorides 3 and 7, respectively. Deprotection of 4 or 8 was achieved in high yields by UV irradiation at room temperature in Pyrex vessels under neutral conditions and exclusion of air. In a similar manner the di­nitroindolines serve as protecting groups for alcohols and phenols; the derived carbamates 5 and 9 can likewise be deprotected photochemically in high yields.

Key words

alcohols - amines - protecting groups - photochemistry - ureas - carbamates - indolines

References and Notes

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13

Previously, carbamate derivatives of 7-nitroindolines have been obtained by prior deprotonation with NaH (ref. 8).