Anionic Fries rearrangements of esters of ortho-iodobenzyl alcohols: rapid routes to oestrone methyl ether and its 9? epimer, and aryl naphthalide lignans
作者:Stephen Horne、Russell Rodrigo
DOI:10.1039/c39920000164
日期:——
A fast, general, low-temperature rearrangement of ortho-iodobenzyl esters, triggered by lithiumâiodine exchange, leads to isobenzofurans which are intercepted in situ by inter and intramolecular DielsâAlder (IMDA) reactions to produce a variety of carbocycles including natural lignans and steroids.
Intermolecularradicaladdition reactions of α-iodo cycloalkenones and a synthetic study of the formal synthesis of enantiopurefawcettimine
作者:Kuan-Miao Liu、Chi-Min Chau、Chin-Kang Sha
DOI:10.1039/b714078a
日期:——
generation of alpha-carbonyl vinyl radicals from alpha-iodo cycloalkenones, the scope of their participation in intermolecular additionreactions with electron-withdrawing olefins are studied and a synthetic study of the formal synthesis of enantiopure fawcettimine using this reaction is described.
Two reaction pathways were elaborated for the practical and convenient synthesis of the title compounds: The first route applies a bromination-dehydrobromination sequence to introduce the double bond into 1-alkoxycarbonyl-2-oxocycloalkylacetic and propionic esters (4a-c, 7a,b). The application of 2,6-lutidine for dehydrobromination of alpha-bromocycloalkanones diesters (5a-c, 8a, b) provides sufficient selectivity to carry out this step without affecting the sensitive ester group. Alternative pathways, involving Michael reaction of diethyl 2-acetylsuccinate or -glutarate with acrolein and subsequent intramolecular aldol condensation, are presented in the case of cyclohex-2-enone derivatives 2a, b.
Catalytic Intermolecular Pauson - Khand Reactions in Supercritical Ethylene
Ethylene is not only a substrate, but also a solvent: Catalytic intermolecular Pauson - Khand reactions of terminal alkynes were carried out in supercritical ethylene to provide 2-substituted cyclopentenones in moderate to high yields [Eq. (1)]. Under these conditions, even a low pressure of CO (5 atm) is sufficient for the reaction to take place.
Korits, V. R.; Sokolov, G. P.; Freimanis, Ya. F., Journal of Organic Chemistry USSR (English Translation), 1985, vol. 21, # 2, p. 273 - 279
作者:Korits, V. R.、Sokolov, G. P.、Freimanis, Ya. F.、Sakhartova, O. V.、Milman, I. A.、et al.