Carbamoyl silanes

V,7V-Diethylcarbamoyl trimethylsilane has been prepared by the reaction of bis(trimethylsilyl) sulphide with bis(A,A-diethylcarbamoyl) mercury (Scheme 30)16. Silylation of the carbamoyl cuprate reagent derived from a lithium amide, by addition of copper(I) cyanide and subsequent exposure to carbon monoxide (1 atm), is also effective75,110. Poor to moderate yields of carbamoyl silanes may be isolated by treatment of lithium silylamides with carbon monoxide and methyl iodide, in a reaction sequence involving a nitrogen to carbon silyl shift in an intramolecular silylation (Scheme 31)111. 

The lithium salts of acyclic secondary amines 92 can be conveniently transformed into the corresponding carbamoyllithiums 89 at —78 °C. Under these reaction conditions they react with trialkyltin chlorides to give carbamoyl stannanes 93 (Scheme 24)98. In the case of benzyl and allyl halides, an alkylation can occur affording products 94. However, when trialkylsilyl chlorides were used as electrophiles no carbamoyl silanes could be detected.. V-Alkyl thiocarbamates 95 can be prepared by reaction of the same intermediates 89 with sulfur followed by. S -alkylation at 0°C (Scheme 24)". 

Carbamoyl silanes 100 could be prepared by reaction of lithium silylamides 97 with CO at room temperature and under pressure (30 atm) followed by reaction with methyl iodide (Scheme 25)101. The intermediate carbamoyllithium 98 suffers a rearrangement of the silyl group to afford a new lithium (silylcarbonyl)amide 99, which is finally methylated. 

A range of densely functionalized five- and six-membered nitrones were formed in this way, and the method is proposed as suitable for the synthesis of the alkaloid laccarin. Under the influence of nucleophilic fluoride sources, including TBAT, a carbamoyl silane undergoes addition to ketones and aldehydes to give a-silyloxyamide products. TBAT can be used in combination with Mc3SiN3 to effect glycosyl azide formation, and finally it can be used to effect self-condensation of some unsaturated carbonyl compounds, a process in which fluoride presumably acts as a base. ... 

N,N-Dimethylaniline) Dimethylbenzene, see Xylene 1,3-Dimethylbutyl acetate Dimethyl carbamoyl chloride Dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate, see Naled Dimethyl ether N-N-Dimethylethylamine Dimethylethoxy silane Dimethylformamide SK... 

The silicon containing (5 5 5) heterocycle 32 has been efficiently synthesized starting from. Y-prolinc 375 via silanes 376, 378, and 379. The final step has been achieved via radical cyclization. The amine 377 was treated with COCl2 and the resulting carbamoyl chloride 378 reacted with PhSeNa to give the radical precursor 379 (84% overall yield from 376). Compound 379 when refluxed with Ph3SnH or Bu3SnH in the presence of AIBN afforded the desired heterocycle 32 in 75% yield (Scheme 81). 

Cunico and Maity published another example of palladium-catalyzed CO-free carbonylation of aryl halides [121]. Depending on the substrate, 2 mol% of either Pd(PPh3)4 or Pd(P Bu3)2 was used to catalyze the reaction of heteroaryl and aryl bromides with A,A -dimethyl-carbamoyl(trimethyl)silane (Scheme 2.10). Tertiary amides were prepared in good yields by direct carbamoylation under their conditions. Remarkably, chlorobenzene, 1-chloro -methoxybenzene, and iodoben-zene gave the desired products in 74, 78, and 60 % yields, respectively. 

Scheme 3-186. Substituion reactions using carbamoyl(trimethyl)silane.

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