(scheme-4) In case of 1,2 dihydroxy benzene 6o, it gives the dibenzyloxy product 7o in 45% yield, along with complex product, benzyloxyimino-acetic acid benzyl ester 19 in 15% yield. The mechanism is not clear, but it is expected the steric hinderance play a key role in the formation of benzyloxyimino-acetic acid benzyl ester 19. (scheme-5)