Chalcogen isothiocyanates

Although very little is known for the reactions of isolated germylenes 146, 147, and 148, diarylgermylene (150) was found to undergo a variety of reactions with olefins, dienes, acetylenes, alcohols, isothiocyanates, elemental chalcogens, and hydrosilanes as in the cases of less hindered, transient germylenes previously reported. 

Further reactions of P-hydridocyclotriphosphazenes (See Section IV,E) have been described. They undergo insertion reactions with aldehydes, ketones, isothiocyanates and electrophilic olefins. Addition of sulfur or oxidation with KMn04 gives thioxo-or oxo-cyclotriphos-phazene derivatives which are methylated at the chalcogen to afford methylthio- and methoxy- cyclotriphosphazenes (36). Hydridocyclo-phosphazenes can also be oxidized to give symmetric and unsymmetric bis(cyclotriphosphazenyl) oxides (35). 

With the exception of an isolated reports on the decomposition of diacyl peroxides in acetonitrile in the presence of copper(II) isothiocyanate and potassium dtiocyanate (equation 32), the only preparative methods available for decarboxylative chalcogenation and phosphorylation make use of the 0-acyl duo-hydroxamates. 

Previously, the synthesis of flve-membered heterocycles containing sulfur, selenium, and tellurium was reported by Sibor and Pazdera (1996). Two different kinds of heterocycles (93-95) can be prepared by the reaction of substrates (92), a chalcogen atom, and isothiocyanate or ketones in the presence of triethylamine under ultrasonic conditions (Scheme 8.29). Beyond the utilization of ultrasound, the authors studied the use of conventional conditions, as well as microwave irradiation. 

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