Synthetic application of biotransformations: absolute stereochemistry and Diels–Alder reactions of the (1S,2R)-1,2-dihydroxycyclohexa-3,5-diene-1-carboxylic acid from Pseudomonas putida

1,cis-2-Dihydroxycyclohexa-3,5-diene-1-carboxylic acid, 2, produced by Pseudomonas putide, U103, was shown via X-ray analysis of its p-bromobenzoylmethyl ester to have (1S 2R) absolute stereochemistry. The stereo- and regio-selectivity of a series of cycloadditions of the methyl ester 3(R = Me) the methyl ester acetonide 5 and the hydroxymethylacetonide 6(R = H) with singlet oxygen, 4-phenyl-4,5-dihydro-3H-1,2,4-triazole-3,5-dione, N-phenylmaleimide and nitrosobenzene have been established. The stereochemistry of the oxygen adduct 7 of 5 was unambiguously assigned by X-ray analysis of 7. The acetonides 5 and 6(R = H) were attacked by the dienophiles anti to the acetonide group. The diol ester 3 underwent attack on the face syn to the diol groups. The regiochemistry of the addition of nitrosobenzene was predominantly with the N–phenyl group distal to the ester function in 3 and 5, but proximal to the hydroxymethyl group in 6(R = H).