methyl 2-(benzenesulfinyl)acetate

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of methyl 2-(phenylsulfinyl)acetate (1 g, 5.04 mmol), 2,2-dimethoxyacetaldehyde (3.15 ml, 10.09 mmol) and piperidine (0.999 ml, 10.09 mmol) in acetonitrile (20 ml) was heated to 60° C. for 18 hr. After cooling to rt, the volatiles were removed in vacuo and the residue was chromatographed on a 5×12 cm silica gel column, eluting with a 0-40% EtOAc/Hex gradient. The pure fractions were concentrated to afford (E)-methyl 4,4-dimethoxy-2-(phenylsulfinyl)but-2-enoate (1.42 g, 4.99 mmol, 99% yield) as a light yellow oil. HPLC retention time=1.23 minutes (PHENOMENEX® Luna 4.6×30 mm S-5 ODS column) eluting with 10-90% aqueous methanol+0.1% TFA over a 2 minute gradient. MS: (M+Na)=307.06. 1H NMR (500 MHz, chloroform-d) δ ppm 3.40 (s, 3H), 3.41 (s, 3H), 3.69 (s, 3H), 5.71 (d, J=7.2 Hz, 1H), 7.07 (d, J=6.6 Hz, 1H), 7.48 (m, 3H), 7.66 (m, 2H). After cooling to rt the volatiles were removed in vacuo the residue was chromatographed on a 5×12 cm silica gel column eluting with a 0-40% EtOAc/Hex gradient The pure fractions were concentrated