Generation and trapping of 1,3-dithian-2-ylidene-substituted ethyl carbene. On the existence of 4,8-dithiaspiro[2.5]oct-1-ene

Abstract

The readily available sodium salt of 2-(1,3-dithian-2-ylidene)acetaldehyde tosylhydrazone 6 could be thermolysed to transient 2-(2-diazoethylidene)-1,3-dithiane 7 and from there to 1,3-dithian-2-ylidene-substituted ethyl carbene 8. Both species gave cycloadditions with different types of alkenes. Evidence is presented for the electrocyclisation of the vinyl carbene to 4,8-dithiaspiro[2.5]oct-1-ene.