SATURATED HETEROCYCLES .225. TERT-BUTYLCYCLOPENTANE DERIVATIVES .8. SYNTHESIS OF TERT-BUTYLCYCLOPENTANE-FUSED PYRIMIDIN-4-ONES

In the reactions of ethyl (1 S)-2-amino-4-tert-butyl-1-cyclopentaneca rboxylate (4) or ,5S)-3-tert-butyl-6-azabicyclo[3.2.0]heptan-7-one (2 ) or S)-2-amino-4-tert-butyl-1-cyclopentanecarboxamide (6) with imida tes or triethyl orthobenzoate, tert-butylcyclopentane-fused dihydropy- rimidin-4-ones (7a-e) were prepared. The azetidinone (2) with lactim e thers furnished pyrrolo-, pyrido- and azepino[1,2-a]pyrimidin-4-ones ( 8-10) in ring-enlargement reactions. Ethyl S)-2-amino-4-tert-butyl-1- cyclopentanecarboxylate (4) and ethyl (1R,2S*,4S*)-2-benzylamino-4-te rt-butyl-1 cyclopentanecarboxylate (5) and potassium cyanate or phenyl isocyanate or potassium thiocyanate or phenyl isothiocyanate, yielded pyrimidine-2,4-diones or 2-thioxopyrimidin-4-ones (11-22).