One-pot synthesis of spiro isochromane-3,3'-piperidines, -3,4'-piperidines and -3,3'-pyrrolidines

Article abstract of DOI:10.1055/s-1993-25832

Spiro isochromane-1-ones 1 were treated with lithium aluminum hydride or Grignard reagents to afford diol intermediates 2, which cyclize in 85% phosphoric acid at 100°C to spiro isochromanes 3 in 72-94% isolated yields.