The synthesis of novel N-heterocycles from 2-azido-, 2-vinylazido- and 2-formyl-1,6-methano[10]annulene-2-carbaldehydes

The preparation of 2-azido-1,6-methano[10]annulene 2 from 2-lithioannulene is described. The annulene 2 underwent ring expansion on thermolysis in the presence of various secondary amines to give novel bridged aza-annulenes of type 3 and also gave 1,3-dipolar addition products. When heated the vinyl azides 13(R1= R2= H) and 13[R1= H, R2= CHC(CO2Et)N3] underwent cyclisation to give the annuleno[3,2-b]pyrroles 14 and 15 respectively. Annulenopyridines such as. 18 were obtained from the iminophosphorane 16via an aza-Wittig reaction with phenyl or allyl isothiocyanate or tolyl isocyanate. Some 2-formyl derivatives 1(R1= CHO) when treated with tosylmethyl isocyanide yielded oxazolylannulenes 19.