... Tetrahedron. Volume 65, Issue 18, 2 May 2009, Pages 3804–3808. ... 16, 16a, 16b, 16c and 16d Oxa and azaspiro derivatives are well-known, 16, 17, 17a, 17b, 17c and 18 but the preparation of corresponding quinazolinone analogues has not yet evolved. ...