A short and efficient annelation sequence for the synthesis of bicyclic intermediates in the total synthesis of strigol and its analogues
摘要:
A new annelation sequence was developed for the bicyclic diones 2, intermediates in the total synthesis of strigol (1) and its analogues. The first step of the sequence is the conjugate addition of nitro alcohols 4 to cyclopentenone 5, followed by an alkylative cyclization step and dehydrogenation.
7-methyl-4-nitro-1-oxohydrindene derivatives. Functional group elaborations of these intermediates lead to a series of the title compounds, which could be readily converted to the tricyclic moieties of strigol and its analogues of biological importance.
Synthesis and Biological Evaluation of the Four Racemic Stereoisomers of the Structure Proposed for Sorgolactone, the Germination Stimulant from Sorghum bicolor
The synthesis of the racemates of the structure 1 proposed for sorgolactone and its three stereoisomers was achieved by confirming the stereostructures of the intermediate (±)-6 and the final product (±)-1 by X-ray analyses. Biologicalevaluation of the products employing clover broomrape (Orobanche minor) seeds revealed that the order of activity as a germinationstimulant was (±)-strigol ≈ (±)-9