Preparation of alpha-diazocarbonyl compounds from beta-lapachone derivatives and other 1,2-naphthoquinones: use of the 2D NMR H-1,N-15 and H-1,C-13 HMBC techniques in assigning regiochemistry

摘要

The assignment of the diazo site in products of the reaction of p-toluenesulfonylhydrazine with P-lapachone, 3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione, and other 1,2-naphthoquinones in methanol solution at room temperature has been accomplished using H-1,C-13 HMBC and 1H,N-15 HMBC NMR experiments. Only one diazo-naphthalenone product was isolated in yields ranging from 50-100% from each reaction. The site of diazo substitution of beta-lapachone and derivatives is the 1-position, in contrast to substitution at the 2-position in 4-MeO-1,2-naphthoquinone. Steric factors, rather than electronic factors, control the reaction site. Along with 2-diazo-1(2H)-naphthalenone, an additional product isolated from the reaction of p-toluenesulfonylhydrazide with 1,2-naphthoquinone was 2-diazo-4-hydroxy-1(2-H)-naphthalenone. Confirmation of the formation of 6-diazo-2,2-dimethyl-2,3,4,6tetrahydro-ZH-benzo[h]cromen-5-one, obtained from beta-lapachone, was achieved using single crystal X-ray diffraction. Copyright (c) 2006 John Wiley & Sons, Ltd.