3-(Benzoylthio)-2-methylpropanoic acid

(+-) 1-(3-Benzoylthio-2-methyl-1-oxopropyl)-1, 2, 3, 4-tetrahydro-2-quinolinecarboxylic Acid 3-Benzoylthio-2-methylpropanoic acid (11.6 g) in toluene (78 ml) was treated with thionyl chloride (4.6 ml). The resulting solution was warmed to 80 for 2.5 hours and then evaporated to dryness under reduced pressure to yield 3-benzoylthio-2-methylpropanoyl chloride.B. Regeneration of (-)-3-benzoylthio-2-methyl-propanoic acid 984 Ml. of methylene chloride, 984 ml. of water and 246 ml. (.246 moles) of 1N sodium hydroxide were mixed in a 4 l. beaker under magnetic stirring. To this mixture was added the (-)-BTMPA-(+)-DHAA salt (246 g.) obtained above. Thereafter, another 246 ml. of 1N sodium hydroxide was added, and the mixture was stirred for ten minutes while adjusting the pH to 10.2-10.5. The resulting aqueous and methylene chloride layers were separated, and the methylene chloride layer was washed with 246 ml. of water. The aqueous layers were combined and washed with 246 ml. of methylene chloride. 496 Ml. of 1N hydrochloric acid were added to the aqueous layer (pH=3). The oil which separated out was extracted with 369 ml. of methylene chloride, and the aqueous layer was washed once more with 123 ml. of methylene chloride. The extracts were combined and washed with 125 ml. of water, and the organic extract was filtered. The filtrate was transferred to a 3 l. 3 necked flask furnished with a condenser, a stirrer and a thermometer, and 984 ml. of hexane were added. The solution was concentrated under reduced pressure to 984 ml. while keeping the pot temperature at 55-40 C. This dilution with 984 ml. of hexane and concentration down to 984 ml. was repeated once. Thereafter, the solution was cooled to 20-25 C. and held at that temperature for 60 minutes. The solids were filtered out and washed twice with 61.5 ml. of hexane. The resulting solid was dried in a vacuum oven at temperatures below 35 C. yielding the product (-)-3-benzoylthio-2-methyl-propanoic acid, 94 g. (86.8 percent yield in step B, 51.4 percent overall yield); m.p. 69.7 C.; [alpha]D25 =-42.3 (AT-147; 2% ethanol).(a) (trans)-1-[D-3-(Benzoylthio)-2-methyl-1-oxopropyl]-4-hydroxy-L-proline, methyl ester (a) (cis)-4-Methoxy-1-[3-(benzoylthio)-2-methyl-1-oxopropyl]-L-proline Interaction of 3-benzoylthio-2-methylpropionyl acid chloride (prepared by treating (1) 5.69 g of methyl (3S)-1, 2, 3, 4-tetrahydroisoquinoline-3-carboxylate hydrochloride are suspended in 50 ml of chloroform, and 5.6 g of triethylamine are added thereto under ice-cooling and stirring. 3-benzoylthio-2-methylpropionyl chloride (which is prepared by heating a mixture of 5.6 g of 3-benzoylthio-2-methyl-propionic acid and 6 ml of thionyl chloride at 60 C. for 2 hours, followed by distillation thereof to remove the excess of thionyl chloride) is dissolved in 10 ml of tetrahydrofuran, and said tetrahydrofuran solution is added dropwise to the suspension obtained above. After the mixture is stirred at room temperature overnight, the chloroform layer is collected therefrom and washed with water, an aqueous sodium bicarbonate solution, diluted hydrochloric acid and water, successively. The chloroform solution is dried and then distilled to remove solvent. The residue thus obtained is purified by silica gel column chromatography (Solvent, toluene-ethyl acetate (4:1)). 8.0 g of methyl (3S)-2-(3-benzoylthio-2-methylpropionyl)-1, 2, 3, 4-tetrahydroisoquinoline-3-carboxylate are obtained as colorless oil. Yield: 80.5 %

Molecular Weight:224.28
XLogP3:2.4
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:5
Exact Mass:224.05071541
Monoisotopic Mass:224.05071541
Topological Polar Surface Area:79.7
Heavy Atom Count:15
Complexity:234
Undefined Atom Stereocenter Count:1
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes