Annulated Three- and Four-Membered Heterocycles

DIMEDONE-ANNULATED THREE- AND FOUR-MEMBERED HETEROCYCLES 

Only few examples were reported related to these ring systems. Moreover, only those fused with three-membered ring mainly containing one heteroatom oxygen were reported. No examples can be found with a four-membered ring containing two heteroatoms. 

The epoxide ring in such fused ring systems has been formed by the epoxidation with f-butylhydroperoxide/Triton-B of the respective double bond in 6 and 7, which were prepared from 2 via the formation of 

Compounds 3 and 13 represented fused four-membered heterocycles, that have been formed by the photochemical irradiation of 2 (R = H) to give 12, via a photo-aza-Claisen rearrangement, in addition to the four-membered ring 13 in a very poor yield. The formation of which has been 

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