Controlling Mode Selectivity in Palladium-Catalyzed Bisdiene Carbocyclizations:  Optimizing for Cyclization-Trapping over Cycloisomerization

Abstract

[reaction: see text] Screening combinations of five catalyst precursors with 13 phosphorus ligands identified cyclization catalysts that favor carbocyclization-trapping with N-hydroxyphthalimide over a competing cycloisomerization mode.

(Diacetoxyiodo)benzene‐Mediated Oxygenation of Benzylic C(sp3)–H Bonds with N‐Hydroxyamides at Room Temperature

“…[5,10] In the presence of Cu(OAc) 2 , NBS (Nbromosuccinimide), and PhI(OAc) 2 , adduct 3 was transformed into 3-hydroxy-2-(perfluorophenyl)-isoindolin-1-one (32) in 58 % yield by formation of a new C(sp 3 )-N bond and removal of the 1,3-dioxoisoindoline group. Gratifyingly, adduct 3 could be used for the construction of isobenzofuran-1(3H)-one 33 by using 1 equiv.…”

nBu4NI-catalyzed intermolecular C–O cross-coupling reactions: synthesis of alkyloxyamines

“…In addition, The obtained PINO adducts could be readily converted to the corresponding alcohols or hydroxylamine species (equation 2). 7 For example, product 3b can be transformed into phenylmethanol 6a in 70% yield by cleavage of the N−O bond with Mo(CO) 6 , while 3n underwent reaction to afford 1-phenylethanol 6b in 78% yield. The reaction of 3b with hydrazine produced O-benzylhydroxylamine 7a in 71% yield.…”

Recent Developments in Palladium-Catalyzed Heterocycle Synthesis and Functionalization

“…For example, Widenhoefer has developed a twostep procedure for the synthesis of disubstituted pyrrolidines bearing 3-hydroxymethyl substituents via a tandem cycloisomerization/hydrosilylation of 1,6-dienes followed by Tamao-Fleming oxidation of the alkylsilyl moiety (eq 21) [35]. Cycloisomerizations of bis(diene) substrates have also been reported [36]. These reactions proceed through intermediate allylpalladium complexes that can be trapped with certain external nucleophiles (eq 22).…”