EPC syntheses employing (2S, 3S) and (2S, 3R) – Tetrahydro-3-Hydroxy-5-Oxo-2,3-Furandicarboxylic acids: syntheses of analogues of Quararibea Metabolite Chiral Enolic-Lactones

Abstract

(2S,3S)- and (2S,3R)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylic acids (Garcinia and Hibiscus acids) have been isolated in large amounts from cheap natural sources and the optical purity of the molecules were asserted by VCD analysis. A systematic literature survey for biologically potent and#947;-butyrolactone based natural products has been conducted. The study revealed that there are several and#947; butyrolactone based molecules which have matching structure and stereochemistry with that of the title compounds. Attempts were made to synthesize analogues of the Quararibea metabolite chiral enolic-and#947;-lactone (3- hydroxy-4,5-(R)-dimethyl-2(5H)-furanone) from (2S,3S)- and (2S,3R)- tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylic acids. Reaction of Dialkyl (2S,3S)- and (2S,3R)-tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylates with POCl3 in pyridine followed by treatment with diazomethane resulted in the isolation of 2S-Dialkyl 4-methoxy-5-oxo-2,5-dihydro-2,3-furandicarboxylates, analogues of the Quararibea metabolite chiral enolic-and#947;-lactone (3-hydroxy-4,5- (R)-dimethyl-2(5H)-furanone). Certainly an unusual and#945;-hydroxylation of and#947;- butyrolactone (dialkyl tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylates) is involving with POCl3. The feasibility of and#945;-hydroxylation with methanesulfonyl chloride failed instead resulted in the formation of aromatic dialkyl 5- [(methylsulfonyl)oxy]-2,3-furandicarboxylates. This clearly indicates the involvement of a (2,3)-sigmatropic rearrangement leading to and#945;-hydroxylation of dialkyl tetrahydro-3-hydroxy-5-oxo-2,3-furandicarboxylates. Trialkyl (1S,2S)- and (1S,2R)-1,2-dihydroxy-1,2,3-propane tricarboxylates was converted to (4S,5S)-4- (2-Hydroxy-2,2-diarylethyl)-2,2-Dimethyl-and#945;,and#945;,and#945; ,and#945; -tetraaryl-1,3-dioxalane-4,5- dimethanols. This TADDOL analogue was found to be effective chiral dopants for the phase transformation of nematic liquid crystal into cholesteric liquid crystal.