Selwyn Yorke - Stereoselective base-induced conversion of naphthalenic precursors into naphthopyrans related to the alphin-derived glucoside B

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      Publication Details (including relevant citation   information):

      Journal of the Chemical Society, Perkin Transactions 1:    Organic and Bio-Organic Chemistry (1972-1999) (1994), (7), 859

      Abstract:

      Trans-5-Benzyloxy-3,4-dihydro-10-methoxy-1,3-dimethyl-1H-naphtho[2,3-c]pyran   I (R = OCH2Ph, R1 = Me, R2 = H) and   trans-3,4-dihydro-10-isopropoxy-7,9-dimethoxy-1,3-dimethyl-1H-naphtho[2,3-c]pyr an   I (R = H, R1 = CHMe2, R2 = OMe) are formed with complete   stereoselectivity by reaction of, resp.,   2-allyl-1-benzyloxy-3-(1-hydroxyethyl)-4-methoxynaphthalene and   the mixt. of (E)- and   (Z)-3-(1-hydroxyethyl)-4-isopropoxy-5,7-dimethoxy-3-prop-2-enylnaphthalene   with potassium tert-butoxide in DMF under nitrogen.  The   benzyloxy substituent of compd. I (R = OCH2Ph, R1 = Me, R2 = H)   is removed in three steps to afford   trans-3,4-dihydro-10-methoxy-1,3-dimethyl-1H-naphthop[2,3-c]pyran   (II).  II and I (R = H, R1 = CHMe2, R2 = OMe) are also   transformed with complete stereoselectivity into the   corresponding pseudoequatorial 4-alcs. III with potassium   tert-butoxide in oxygenated DMSO and DMF, resp.

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