Other Base-Labile Carbamates

2-(Trimethylsilyl)ethyl carbamate (Teoc) can be selectively removed with fluoride (e.g. TBAF, THF, 50 °C, 5-20 h [147,286,287]), or by acidolysis with TFA [153,288]. 2-Nitrofluorenylmethyl carbamates can be cleaved photolytically or by treatment with bases [289]. 

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A very mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides 409 is based on the use of (tosylimino)phenyl-X. -iodane, PhINTs, as the oxidant (Scheme 3.165) [506]. Owing to the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides 409 (R = aryl), which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates 410, or their subsequent conversion into stable carbamates 411 by treatment with alcohols. Based on the previously reported mechanistic studies of the Hofmann rearrangement using other hypervalent iodine reagents [489,490,496], it is assumed that the reaction... 

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