Cyclizations of enolates onto aromatic rings via the photo-SRN1 reaction. Preparative and mechanistic aspects

Photoinduced cyclization of mono- and dianions of N-acyl-o-chloranilines. A general oxindole synthesis

“…Ammonia,2 mono-and dimethylamine,3 tetrahydrofuran,4 and dimethyl sulfoxide5 are typical of the bases that can effect the unsymmetrical cleavage of the boranes, and extensive work has been reported in the literatures6 on the chemistry of the boronium cation H2BL2+. Many other Lewis bases cleave the boranes "sym-0002-7863/80/1502-3647501.00/0 metrically"1 to give the base adducts of borane(3) and triborane (7).…”

“…C 1971, 1375. e Satisfactory elemental analysis was obtained for this compound. 7 Yield was determined by GC. g Irradiated for 0.5 h. * Bruce, J. M.; Sutcliffe, F. K. J. Chem.…”

Evidence for intermolecular hydrogen atom transfer in photostimulated SRN1 reactions involving ketone enolates

“…Similarly, ester enolates containing ß hydrogens effect reduction of aryl halides by intermolecular hydrogen atom transfer. 12 Accordingly, we postulate that phenyl radical, besides adding to 1 (eq 3), abstracts a ß hydrogen as shown in eq 7.…”

“…Besides the ABX pattern, two septets arising from the methine protons at C-2 and C-8 are distinguishable at 2.67 (J = 6 Hz) and 3.07 (J = 7 Hz), as well as a methyl multiplet (21 H) at 1.10. The proton-decoupled 13C NMR spectrum of 4 contains two carbonyl resonances at 217.4 and 219.3 ppm, along with 12 peaks attributable to saturated carbon atoms. 10 The NMR spectrum of an authentic sample of 3, prepared from 2,4dibromo-2,4-dimethyl-3-pentanone by means of zinc-copper couple11 or by the action of acetyl peroxide on 2,4-dimethyl-3-pentanone,1 consists of a doublet at 1.04 (J = 7 Hz), a singlet at 1.24, and a septet at 3.14 (J = 7 Hz) in a ratio of 12:12:2.…”

Formation of 2-halomethylene-4-cyclopentene-1,3-diones andor 2-halo-1,4-benzoquinones, total synthesis of methyl linderone and Wacker-type oxidation of aryl-substituted alkenes

“…The selective installation of an aryl group in the α-position of a carbonyl group has been an intense research subject over the past 40 years 98 and many synthetic methods have been reported [99][100][101][102] to construct these scaffolds, such as reaction of an enolate with a derivative of benzyne, 99 aryl reagents, 102 Grignard reaction of benzamides with benzylmagnesium halides, 103 Friedel-Crafts reaction of phenols with various phenylacetic acids in BF 3 -Et 2 O, 104 and so on.…”