Succinic anhydride → 3-(2-Thenoyl)propionic acid
Reaction equation
[S:1]1[CH:5]=[CH:4][CH:3]=[CH:2]1.[C:6]1(=[O:12])[O:11][C:9](=[O:10])[CH2:8][CH2:7]1>>[S:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[C:6](=[O:12])[CH2:7][CH2:8][C:9]([OH:11])=[O:10]Participants
Procedure
Thiophene (a) is reacted with succinic anhydride (c) under Friedel-Crafts reaction conditions to afford 4-(2-thienyl)-4-oxobutyric acid (XII). Substitution of benzene (b) in the above reaction affords 4-phenyl-4-oxobutyric acid (XVII). ##STR18## The oxobutyric acids of formulas (XII) and (XVII) obtained in Step 1 above, are reacted with a suitable 1,2-dithiol (d), R3 and R4 are each either hydrogen or methyl, in an aromatic solvent such as benzene, toluene or xylene, in the presence of catalytic amounts of p-toluenesulfonic acid at a temperature range of 25° to 120° C and, preferably, from 75° to 110° C while azeotroping the water formed in the reaction. Alternatively, the reaction is conducted in a C2 -C5 alkanoic acid, preferably, acetic acid in the presence of an acid catalyst such as boron trifluoride/methanol, boron trifluoride/ether, ZnCl2 /Na2SO4, HCl/ether, and the like, at the temperature range specified above, to afford 2-(2-thienyl)-1,3-dithiolanepropionic acid (XIII) and 2-phenyl-1,3-dithiolane-2-propionic acid (XVIII), respectively. R3 and R4 are as hereinabove defined. ##STR19## The dithiolane propionic acids of formulae (IIIa) and (IIIb) are converted to the corresponding acid chlorides of formulae (XIV) and (XIX) with oxalyl chloride or thionyl chloride (with a small amount of DMF added if desired) in an inert anhydrous solvent selected from the group consisting of benzene, toluene, xylene, chlorobenzene, at a temperature range of about 0° to 30° C and preferably 15° to 30° C. ##STR20##
Sources & evidence
- ORD record
- ord-e1a466d4c27b4ed4915d72b82a38f497
- Source dataset
- uspto-grants-1978_02
- Patent number
- US04075228
Reaction notes
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