(R)-(+)-p-Tolylsulfinylacetic Acid

[88981-65-1]  · C9H10O3S  · (R)-(+)-p-Tolylsulfinylacetic Acid  · (MW 198.26)

(optical resolution of amines1,3,4)

Physical Data: [a]D = +143.5° (acetone, c = 33.0). The absolute configuration of this reagent (and other arylsulfinyl acetic acids) is characterized by two CD Cotton effects which are observed in the presence of the metal cluster [Mo2(OAc)4] in DMSO solution above 300 nm.2

Preparative Method: prepared by carboxylation of (R)-(+)-Methyl p-Tolyl Sulfoxide carbanion generated with Lithium Diisopropylamide (eq 1).1

Optical Resolution of Indole Alkaloid Precursors.

This reagent has been used for optical resolutions of tetracyclic alkaloids such as 10,22-dioxokopsane (1)1 and kopsinine (2).3

The racemic tetracyclic amine (3) can be coupled to (R)-(+)-p-tolylsulfinylacetic acid using the modified carbodiimide reagent 1-Cyclohexyl-3-(2-morpholinoethyl)carbodiimide Metho-p-toluenesulfonate to give the diastereomeric sulfinyl amides (4) and (5) (eq 2), which are readily separated by HPLC.1,3

Similarly, in a total synthesis of strychnine, the optical resolution was carried out by separation of the sulfinyl lactam diastereomers (7) and (8), which were obtained from the heptacyclic indole alkaloid precursor (6); this was first transformed with (R)-(+)-p-tolylsulfinylacetic acid into the corresponding sulfinyl amide and then converted to the diastereomeric lactams (7) and (8) by an intramolecular conjugate addition (eq 3).4

1. Magnus, P.; Gallagher, T.; Brown, P.; Huffman, J. C. JACS 1984, 106, 2105.
2. Drabowicz, J.; Mikolajczyk, M. Croat. Chem. Acta 1989, 62, 423.
3. Magnus, P.; Brown, P. CC 1985, 184.
4. Magnus, P.; Melvyn, G.; Bonnert, R.; Kim, C. S.; McQuire, L.; Merritt, A.; Vicker, N. JACS 1992, 114, 4403.

Guy Solladié & Françoise Colobert

University Louis Pasteur, Strasbourg, France

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