Terminal oxidative carbonylations, palladium® chloride

Terminal alkenes could be efficiently aminated by nonhindered secondary amines in a process requiring 1 equiv. of palladium(II) chloride, 3 equiv. of amine and a reduction at temperatures below -20 C (path a, Scheme 5) 21,22 however, primary amines and/or internal alkenes were less efficient, producing only 40-50% yields of amination product. Oxidative cleavage of the unstable o-alkylpalladium(II) in the presence of a nucleophile resulted in vicinal oxamination or diamination of the alkene (path b).23,24 Car-bonylation resulted in the isolation of stable o-acylpalladium(II) species (path c),23 which were oxidatively cleaved to give 3-amino esters (path d)26 or further carbonylated to give y-amino-a-ketoamidei (path e).27... 

The one-pot synthesis of 2-substituted-3-carboxychromones is readily attained by the reaction of 3-oxo-3-(2,6-di luorophenyl)propanoates and acyl chlorides (13CC5313) and of 3-[2-(methoxymethoxy)phenyl]propio-lates and aldehydes followed by DDQ oxidation of the formed chroma-nones (13T647), via transition metal-free approaches. Palladium(II) -catalyzed cascade carbonylative cyclization of 2-bromophenols and terminal alkenes gives chromones 44 in moderate to good yields. Variation on the amine used in the catalytic system led to aurones 45 as major products (Scheme 74) (13TL1802). 

Quinazolinones are an important class of fused heterocycles that have been reported with remarkable activities in biology and pharmacology such as anticancer, antiinflammatory, anticonvulsant, antibacterial, antidiabetic, hypolipidemic, and protein tyrosine kinase inhibitors. Alper and Zheng reported a palladium-catalyzed cyclocarbonylation of o-iodoanilines with imidoyl chlorides to produce quinazolin-4(3H)-ones in 2008. A wide variety of substituted quinazolin-4(3H)-ones were prepared in 63-91% yields (Scheme 3.27a). The reaction is believed to proceed via in situ formation of an amidine, followed by oxidative addition, CO insertion, and intramolecular cyclization to give the substituted quinazolin-4(3H)-ones. Later on, a procedure was established based on generating the amidine in situ by a copper-catalyzed reaction of terminal allq nes, sulfonyl azide and o-iodo-anilines. The desired quinazolinones can be produced by carbonylation with Pd(OAc)2-DPPB-NEt3-THF as the reaction system. In the same year, Alper s group developed a procedure for 2,3-dihydro-4(lH)-quinazolinone preparation. The reaction started with the reaction of 2-iodoanilines and N-toluenesulfonyl aldimines followed by palladium-catalyzed intramolecular... 

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