Isothiocyanates with organometallic

Isocyanates can be used as the source of the N(3)-C(4) unit by reaction with organometallic intermediates. For example, the reaction of ethyl 2-(bromophenyl)imidates 875 with lithium metal, followed by quenching of the lithiated intermediate 876 with phenyl isothiocyanate gave 3-phenyl-2-substituted 4(3//)-quinazolinethiones 877 <1996SC3167>. 

In sharp contrast to the thioketenes, carbon disulfide S=C=S, carbon oxysulfide 0=C=S and the isothiocyanates R-N=C=S are stable compounds although highly reactive, and are widely used in organosulfur chemistry. Some of their reactions with organometallics have been mentioned previously (see Section 2.8.3). 

Organometallic dithiocarbimates are also known. Thus, a diarylgermanium phenyldithiocarbimate, Tbt(Tip)GeS2C=N-Ph, was obtained from the kinetic-ally stabilized diarylgermylene Tbt(Tip)Ge in a reaction with phenyl isothiocyanate, via [2+2] cycloaddition of a diarylgermanethione [Tbt(Tip)Ge=S] intermediate, evidenced by electronic spectroscopy.425... 

The reactions of covalent azides with the isocyanate system are summarized in Scheme 41. Addition of organic azides and azide ion to isocyanates occurs at the —N=C— bond and gives 1,4-disubstituted tetrazolin-5-ones (221 Scheme 41). The reaction of organic azides with isothiocyanates is a complicated reaction giving a mixture of five different products of which the tetrazoles (223) are minor constituents and the remaining compounds are sulfur heterocycles. Organometallic azides, and also azide ion, add to the —N=C—... 

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