- Facile synthesis of dihaloheterocycles via electrophilic iodocyclization
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An efficient and facile electrophilic iodocyclization for the synthesis of various O-, N-, and S-containing dihaloheterocycles has been developed. A wide range of the substituted propargyl alcohols having -OH, -NTs, and -SAc functional groups reacted with molecular iodine or bromoiodine at ambient temperature to produce the corresponding dihalogenated O-, N-, and S-containing five- and six-membered heterocycles in good to high yields; Under optimized solvent conditions, the reactions of various substituted but-2-yn-1-ones bearing -OH, -NTs, and -SAc functional groups at C4-position, with iodine or bromoiodine at ambient temperature afforded the corresponding 3,4-diiodo- and 3-bromo-4-iodo-substituted furans, pyrroles, and thiophenes in good to high yields. Further transformation of the resulting iodine- or bromine-containing products to polyaromatics potentially of useful as organo-material intermediates has been investigated.
- Yang, Fan,Jin, Tienan,Bao, Ming,Yamamoto, Yoshinori
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supporting information; scheme or table
p. 10147 - 10155
(2012/01/03)
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- Attempts at vinyl radical carbonylation through cyclization onto carbonyl and cyano groups
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Sulfanylvinyl radicals 4-6, 16, produced from toluenesulfanyl radical addition to alkynes 1-3, 15, gave only products arising from cyclization onto the thiophenyl ring and H-abstraction. No products were obtained deriving from possible 5-membered cyclization onto the esteric or thioesteric carbonyl group. Similar results were obtained from toluenesulfanyl radical addition to alkynyl nitriles 20 and 24, which did not provided any evidence for 5- or 6-membered vinyl radical cyclization onto the aliphatic cyano group. In contrast, both toluenesulfanyl- and benzenesulfanyl- vinyl radicals 32 and 37a smoothly cyclize onto the aromatic cyano group leading to ketones 35 and 39. This protocol represents a novel indirect radical carbonylation and provides a useful synthetic approach to indenones.
- Montevecchi, Pier Carlo,Navacchia, Maria Luisa,Spagnolo, Piero
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p. 8207 - 8216
(2007/10/03)
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