2-Chloroethyl isocyanate is used as a reagent and building block in chemical synthesis. In particular, it is used in the preparation of functionalized aminobenzoboroxoles which are potential anti-cancer agents and also the synthesis of 3-(2-chloroethyl)-5-methyl-6-phenyl-8-(trifluoromethyl)-5,6-dihydropyrazolo[3,4-f][1,2,3,5]tetrazepin-4-(3H)-one which also exhibit antiproliferative activity. Molecular Formula: C3H4ClNO Molecular Weight: 105.52