- Decarboxylative benzylations of alkynes and ketones
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Benzyl esters of propiolic and β-keto acids undergo catalytic decarboxylative coupling when treated with appropriate palladium catalysts. Such decarboxylative couplings allow the benzylation of alkynes without the use of strong bases and/or organometallics. This allows the synthesis of sensitive benzylic alkynes that are prone to undergo isomerizations under basic conditions. Additionally, decarboxylation facilitates the site-specific benzylation of diketones and ketoesters under mild, base-free conditions. Ultimately, the methodology described expands our ability to cross-couple medicinally relevant heterocycles.
- Torregrosa, Robert R. P.,Ariyarathna, Yamuna,Chattopadhyay, Kalicharan,Tunge, Jon A.
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supporting information; experimental part
p. 9280 - 9282
(2010/10/20)
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- The Pyrolysis of Phenylnaphthalene-dicarboxylic Anhydrides: Products of Ring Contraction and of Radical Cyclization
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Naphthalene-1,2-dicarboxylic anhydrides with neighbouring phenyl substituents give on flash vacuum pyrolysis (850-900 deg C/ 0.02-0.04 mm) ring-contracted carbenes which insert into the phenyl groups.The 8-phenyl anhydride (7) gives acephenanthrylene (10) as the major product, and the 3-phenyl anhydride (15) gives 1,2:4,5-dibenzopentalene (indenoindene) (18).The anhydides (7) and (15) were synthesized by pyrolisis of the corresponding 1-naphthylmethyl propynoates (2) and (13) through a new one-step process of intramolecular Diels-Alder addition/retro-Diels-Alder elimination of acetylene. 1-Phenylnaphthalene-2,3-dicarboxylic anhydride (19) on pyrolysis at 960 deg C/0.02 mm gives fluoranthene (11) as the major product.The behaviour of the 1-C6D5 compound (24) suggests involvement of radical cyclization process.
- Anderson, Mark R.,Brown, Roger F. C.,Coulston, Karen J.,Eastwood, Frank W.,Ward, Annemarie
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p. 1137 - 1150
(2007/10/02)
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