Using the transformation of allyl 2-nitrophenyl thioethers to 3,4-dihydro-2H-1,4-benzothiazines as an example the reductive cyclization of Ï-nitroalkenes to saturated N-heterocycles can be performed highly selective and with high yields if a combination of MoO2Cl2(dmf)2 as a catalyst and Ph3P as reducing agent are employed.