Synthesis of Vitamin K and Related Naphthoquinones via Demethoxycarbonylative Annulations and a Retro-Wittig Rearrangement
作者:Dipakranjan Mal、Ketaki Ghosh、Supriti Jana
DOI:10.1021/acs.orglett.5b02920
日期:2015.12.4
Anionic annulations of 3-nucleofugal phthalides with α-alkyl(aryl)acrylates involving a demethoxycarbonylation provide a succinct synthesis of vitamin K and related naphthoquinones. Also reported is a new cascade reaction stemming from a Cope–retro-Wittig rearrangement. This cascade leads to direct formation of 1-hydroxy-4-prenyloxynaphthalene-2-carboxylates from the corresponding α-prenyl acrylate
Efficient and general conditions for the formation of stereodefined trisubstituted alkenes by using the rhodium‐catalyzed reaction of unactivated Baylis–Hillman adducts with either organoboronic acids or potassiumtrifluoro(organo)borates are reported (see scheme).
Methyl 4-oxothiolane-3-carboxylate and methyl 2-methyl-4-oxothiolane-3-carboxylate anions as synthetic equivalents of α-acrylate and α-crotonate anions. Formal synthesis of integerrinecic acid
作者:Pier Giovanni Baraldi、Mario Guarneri、Gian Pierp Pollini、Daniele Simoni、Achilla Barco、Simonetta Benetti
DOI:10.1039/p19840002501
日期:——
(8a–e) of methyl4-oxothiolane-3-carboxylate (4) and methyl2-methyl-4-oxothiolane-3-carboxylate (5) gave good yields of the α-substituted acrylates (7a–h) and α-substituted crotonates (9a–e); thus the corresponding heterocyclic anions (1a) and (1b) could be considered to be syntheticequivalents of α-acrylate and α-crotonateanions respectively. A formalsynthesis of integerrinecicacid (10) is reported
subsequent boron-trifluoride etherate catalyzed methanolysis of the resultant carbinol acetals . Treatment of α-acetylketene dithioacetals and with methylmagnesiumiodide afforded the carbinol acetals and respectively which under above sequence of reactions yielded the corresponding α-isopropylidene-γ-butyrolactones and in good yields.