Elkapin,Goedecke,W. Germany,1977
To a stirred solution of 20 g (0.1 mol) 2-carbethoxymethylene-3-methyl-4-
thiazolidinone in 120 ml chloroform is added, dropwise, a solution of 5 ml (0.1
mol) bromine in 20 ml chloroform. The solvent is removed by distillation and
the residue crystallized from methanol to yield 18 g (65%) of 2-
carbethoxymethylen-3-methyl-5-bromo-4-thiazolidinone, MP 76°C.
To a solution of 28 g (0.1 mol) 2-carbethoxymethylene-3-methyl-5-bromo-4-
thiazolidinone prepared as described in 200 ml benzene is added (0.2 mol)
piperidine and the mixture is allowed to stand for 3 hours at 25°C. The
resulting suspension is filtered to remove the precipitated piperidine
hydrobromide and the filtrate is evaporated to dryness. The residue is taken
up in ether, filtered and the filtrate saturated with dry hydrogen chloride to
yield the hydrochloride salt of 2-carbethoxymethylene-3-methyl-5-piperidino-
4-thiazolidinone, MP 158°C to 159°C.
