Amino-, Alkoxy-, and Alkylthio-Isocyanates and -Isothiocyanates, RX-NCY, their Isomers RX-YCN and RX-CNY, and their Rearrangements

Hetero-substituted isocyanates and isothiocyanates RX-NCY (X - R2N, RO, or RS; Y - O or S) and the isomeric cyanates RX-OCN, thiocyanates RX-SCN, nitrile oxides RX-CNO, and nitrile sulfides RX-CNS are highly reactive compounds, often transient at room temperature. The chemistry of these compounds is reviewed. A number of rearrangement reactions is described, particularly [ 3,3]-sigmatropic shifts, e.g. PhX-NCY -> o-HX-C6H4-YCN (X = NR, O, S; Y = O, S); and retro-ene type reactions, RCH2X-NCY -> RCH=X + HYCN (X = NR, O, S; Y = O, S). In addition, potential 1,4-shifts of substituent groups of the type R-Y-CNX -> R-X-N=C=Y; 1,3-shifts R-C(=Y)-N=X -> R-X-N=C=Y; and 1,2-shifts R-C(=Y)-N=X -> R-Y-CNX were identified computationally.