Enantiospecific Syntheses of (+)-Crotepoxide, (+)-Boesenoxide, (+)-β-Senepoxide, (+)-Pipoxide Acetate, (−)-iso-Crotepoxide, (−)-Senepoxide, and (−)-Tingtanoxide from (−)-Quinic Acid¹

Abstract

A convenient strategy that is ideally suited for the construction of all the naturally occurring cyclohexane diepoxides and cyclohexene epoxides is described. The key intermediate 12, a 1,3-cyclohexadiene, has been prepared from (−)-quinic acid in 11 steps with 18% overall yield. Singlet oxygen photooxygenation of the 1,3-cyclohexadiene followed by rearrangement of the resultant endoperoxides with either cobalt-meso-tetraphenylporphyrin or trimethyl phosphite afforded enantiopure (+)-crotepoxide, (+)-boesenoxide, and (−)-iso-crotepoxide or (−)-senepoxide, (+)-β-senepoxide, (+)-pipoxide acetate, and (−)-tingtanoxide, respectively.

Cyclohexadiene-trans-diols as versatile starting material in natural product synthesis: short and efficient synthesis of iso-crotepoxide and ent-senepoxide

“…In comparison, Shing et al synthesized senepoxide starting from quinic acid in 17 steps. 13 Analytical data of ent-senepoxide 12 were identical with the literature data of Shing. 13 Analytical data we found for 1,2,3,4-tetra-epi-crotepoxide 15 are identical with those White and coworkers reported for 3,4,5,6-tetra-epi-crotepoxide.…”

Polyoxygenated cyclohexene derivatives from Monanthotaxis congoensis

“…Several have been reported to have biological activity, including antitumor (Kupchan et al, 1969) and antimicrobial (Wirasathien et al, 2006) activities. The polyoxygenated cyclohexenes are synthetically accessible targets for drug development, as evidenced by the reported stereoselective syntheses of 9 and other related compounds (Shing and Tam, 1998). …”

New free radical scavenging neolignans from fruits ofPiper attenuatum

“…After comparing their physicochemical and spectrometric data with those reported in the literature, they were identified as known compounds and confirmed as denudatin B(1) iso-4’, 5’-dimethoxy-3, 4-methylenedioxy-2’-oxo-Δ 3’,5’,8’ -8.1’-lignan (2),[ 8 9 ] lancifolin D (3),[ 10 ] denudatin A (4),[ 11 ] wallichinine (5),[ 12 ] piperenone (6),[ 13 ] lancifolin C (7),[ 12 ] 2-oxo-piperol B (8),[ 14 ] piper kadsin A (9),[ 15 ] and crotepoxide (10). [ 16 ] Structure of these compounds is shown in [ Figure 1 ].…”