T-Butyl carbamate

Table II. Infrared Absorption Data on the Cure of (t-Butyl Carbamate) Terminated Urea-Urethane Coating3...

Bromophenylazo)-2/-toluene, 309 (2-BromophenyI)-iVM7-azoxy (2-hydroxy-5-methylbenzene), 358 p-Bromophenylurea, 138-139 Bromopropadiene, 17 2,3-Butadienoic add, 16 iV-l-Butenylpiperazine, 92 Butter yellow, hazard of, 291 f-Butylamine, oxidation of, 323 -Butyl azide, 269 f-Butyl-OlW-azoxymethane, 349 t-Butyl p-Bromophenylazoformate, 328 t-Butyl 2-(p-bromophenyl)carbazate, 328 H-Butyl carbamate, 238-239 t-Butyl carbamate, 241-243... 

The two commonest examples are the benzyl carbamates (CBZ derivatives) (4) and the t-butyl carbamates (BOC derivatives) (5) where the amino group is protected by the benzyloxycarbonyl or the t-butyloxycarbonyl groups respectively. 

Koizumi and co-workers used the optically active allylic chloroselenuranes bearing the 2-exo-hydroxyl-10-bornyl group to obtain optically active allylic amines [41]. The treatment of allylic selenides with f-BuOCl gave the corresponding allylic chloroselenuranes as the only product. Benzyl carbamate, t-butyl carbamate, p-tosylamide, and diphenylphosphinamide were selected as the AT-protected amines for selenimide formation. The nucleophilic reaction of... 

Koch has reported that the irradiation of 2-ethoxypyrrolidin-5-one (3) and related derivatives yields 1-ethoxycyclopropyl isocyanates (4) or the corresponding t-butyl carbamates (5) (equation 1). This procedure has been developed into a general... 

Another facile method of methyl ation of amines consists of their transformation into carbamates, which are reduced in situ either by LAH [REl] or by NaBH4 in the presence of AcOH or CF3COOH in dioxane or THF [GNl]. However, under the latter conditions, the t-butyl carbamates react poorly (Figure 3.74). 

The p-bromobenzyl ester has been used to protect the 3-COOH group in aspartic acid. It is cleaved by strong acidic hydrolysis (HF, 0°C, 10 min, 100% yield), but is stable to 50% CF3COOH/CH2CI2 used to cleave t-butyl carbamates. It is five to seven times more stable toward acid than a benzyl ester. It may also be cleaved by hydrogenolysis, but in this case HBr may be liberated do to bromine hydrogenolysis. 

Carbamates possess a more electron-rich nitrogen than amides or sulfonamides, and the intermolecular reaction of t-butylcarbamate with aryl halides to form t-Boc-protected anilines has been realized (Eq. 30). As one might expect from the increased rates for amine and indole arylation using the Pd(dba)2/P(t-Bu)3 catalyst, it is this system that allows for the arylation of i-butylcarbamate. Reaction of other carbamates, such as methyl or benzyl carbamate and oxazolinone, occurred in lower yield. However, reaction of t-butyl carbamate with bromoarenes occurred at 100 °C in yields ranging from 62% to 86% with electron-rich, electron-neutral, and sterically hindered or unhindered bromoarenes. Reactions of chloroarenes were again slower, but did occur at 130 °C to give Boc-protected aniline in 59% yield for reaction of chlorotoluene. 

---