Hypoglycemic Thiazolylpyridinium Salts 891give colorless needles of 9, mp 73-74°, nmr consistent. Anal.(C4H,ClaNS) C, , N, S.2,2-Dimethylthiazolidine Hydrochloride (10).-Thiol 1 (16.84 g, 148 mmoles) was dissolved in MeOH (25 ml) and excess Me2-CO (300 ml), and the mixture was heated under reflux for 8.5 hr. Evaporation of solvent gave a residue (20.3 g), mp 162-166°, which was crystallized three times from MeOH by addition of Et20 to give 10 as colorless needles (8.6 g, 38%), having constant mp 170-171.5°( lit.50 164-165°). Anal. (C6H12C1NS) C, H, S.2-Benzoylthiazolidine Hydrochloride (11).-Thiol 1 (5.50 g, 48.5 mmoles) and phenylglyoxal hydrate (7.60 g, 50 mmoles) were heated together at ca. 85°for ca. 5 min; the mixture then was dissolved in MeOH (30 ml) and Et20 (120 ml) was added to incipient turbidity. Cooling gave colorless 11 (4.4 g, 39%), mp 151-153°dec. Recrystallization three times from MeOH by addition of Et20 gave 11 with a melting point of 151.5-152.5°d ec, nmr consistent. Anal. (CioHi2C1NOS) C, , N, S.Spiro [2,3-dihydroindole-3,2'-thiazolidine] -2-one Hydrochloride (12).-Finely powdered isatin (10.95 g, 75 mmoles) was slowly added to thiol 1 (8.5 g, 75 mmoles) in f-PrOH (80 ml) to give a red mixture which, after being stirred for 24 hr at ca. 25°, became pale brown. Filtration separated pale brown 12 (15.4 g, 85%), mp 200-203°dec. A sample was recrystallized three times from MeOH by addition of Et20 and had a constant melting point of 203-204°d ec; ir (KBr), 2370, 1735 (amide C=0) cm-1. Anal. (CioHuCINiOS) C, , N, S. D-5,5-Dimethylthiazolidine-4-carboxylic Acid (13).-n-Penicillamine (35 g, 235 mmoles)10 was dissolved in 45% aqueous HCHO (200 ml, 3.0 moles). Within ca. 5 min, solid started to separate. The mixture was stirred for ca. 20 hr. Filtration then removed the colorless intermediate 14 (29 g, 69%), mp 111-112°, after a wash with dioxane then Et20 and drying over silica gel; ir