4-Piperidino-2-naphthol → 3,3-dianisyl-6-piperidino-3H-naphtho[2,1-b]pyran

Participants

Reaction Steps

1-Chloro-4-piperidino-2-naphthol (3.0 g;0.0115 mol), prepared as in 1(a) above, dissolved in 1.25M aqueous NaOH (100 ml) was stirred and heated to 75°-80° C. To the solution was added (50/50) Raney Nickel (14.0 g) portionwise over 1 hour. The mixture was stirred for 1.5 h, cooled then filtered through celite with washing (3×2M NaOH). The filtrate was neutralised with conc. HCl and extracted into CH2Cl2, dried and evaporated to yield crude 4-piperidino-2-naphthol (1.46 g;56%) as a red-orange oil. Purification by flash chromatography over silica (CH2Cl2) gave 4-piperidino-2-naphthol (of structure 4a below) as a red oil. ##STR16## (c) A mixture of 4-piperidino-2-naphthol (1.00 g; 0.0044 mol) , prepared as described in 1(b) above, 1,1-dianisylprop-2-yn-1-ol(1.18 g;0.0044 mol), acidic alumina Brockmann 1 (4 g) and toluene (40.0 ml) was heated and stirred for 1.5 h, cooled and filtered. The filtrate was washed with 2M NaOH then water, dried and evaporated to give a red gum. Purification of the gum by flash chromatography over silica (20% ethylacetate in hexane) affored an orange gum which upon trituration with pet. ether (40-60)/diethyl ether yielded 3,3-dianisyl-6-piperidino -3H-naphtho[2,1-b]pyran (of structure 5a below) as an off-white solid (5% yield), m.pt. 114°-119° C. ##STR17##

Provenance & Evidence