STEREOSELECTIVE TOTAL SYNTHESIS OF RACEMIC GRANDISOL. AN IMPROVED CONVENIENT PROCEDURE
(+/-) Grandisol has been stereoselectively synthesized in a 31 percent overall yield by a practical and convenient procedure employing the Salomon photobicyclization as the key-step.
Utilization of Selenium-directed Cycloadditions: Concise Synthesis of (+/-)-Fragranol
The reaction of 2-(phenylseleno)prop-1-ene 1 and methyl vinyl ketone 2 in the presence of EtAlCl2 gave the cycloadducts 3a and 3b.A radical substitution of the adducts 3a and 3b with allyltributyltin gave the allylated cyclobutane product, which was transformed into the cyclobutane natural product, (+/-)-fragranol.Stereoselective radical substitution using the ethylene glycol ketals of compounds 3a and 3b was also achieved.
Practical Preparation of Bicyclohept-3-en-6-ones and its Utilisation in Stereoselective Total Synthesis of Grandisol and Lineatin via a Versatile Intermediate.
New and efficient stereoselective total syntheses have been devised for racemic grandisol and lineatin, two important components of pheromonic blends.They are based on the utilisation of 1,4-dimethylbicyclohept-3-en-6-one as a pivotal intermediate.This compound, as well as other bicyclohept-3-en-6-ones, are now easily available by a practical bicyclization of the corresponding 3-hydroxy-6-alkenoic acids.