Isocyanates, addition with Grignard reagents

The addition of Grignard reagents to isocyanates gives, after hydrolysis, N-substituted amides. This is a very good reaction and can be used to prepare derivatives of alkyl and aryl halides. The reaction has also been performed with... 

Anilides and a-Naphthalides. The Grignard reagents prepared from alkyl halides react with phenyl isocyanate (CgHjN=C=0) or with a-uaphthy l isocyanate (C,oH, N=C=0) to yield addition products that are converted by hydrolysis into anihdes and a-naphthalides respectively RX + Mg —> RMgX... 

The 4-hydroxy compound (108) formed on addition of an aryl Grignard reagent to 7-chloro-2-methoxy-3/f-benzo-l,4-diazepine 4-oxide can be dehydrated by heating either with phenyl isocyanate or V,V -dimethylpiperazine. Dehydration with phenyl isocyanate gave the 57/-isomer (109) while heating with V,V -dimethylpiperazine furnished the 3/7-isomer (110). Compound (109) could also be converted into the (110) on heating with V,V -dimethylpiperazine <77ACS(B)70l>. 

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