Keywords: cycloaddition; domino reaction; electrocyclic reactions; photochemistry; stereoselective synthesis; terpenoids EN cycloaddition domino reaction electrocyclic reactions photochemistry stereoselective synthesis terpenoids 1343 1355 13 07/11/23 20230725 NES 230725 Graph 1 Introduction This is a personal account on a reaction cascade that our group has been working on for roughly six years. [72] First, the xanthate I rac i - B 46 b was quantitatively generated from alcohol I rac i - B 45 b before treatment with azobisisobutyronitrile (AIBN) and phosphinic acid resulted in the desired de-oxygenated compound I rac i - B 47 b with a 96% yield. Along these lines, the use of compound I rac i - B 36 b , bearing a methyl group at the -position relative to the carbonyl group and two methyl groups on the alkene, as the starting material for the photochemical reaction cascade would lead to the desired intermediate I rac i - B 34i b . The authors suggested that the reaction proceeds via intermediate I rac i - B 9 b , obtained upon the initial I ortho i photocycloaddition, followed by a thermal disrotatory ring opening resulting in the cycloocta-1,3,5-triene derivative I rac i - B 10 b . [Extracted from the article]