3722-74-5Relevant academic research and scientific papers
Reactions of γ-arylalkanols via aryl radical cation and alkoxyl radical intermediates. Part 3. Reactions of 3-arylprop-1-yl hydroperoxides with iron(II) in the presence of copper(II)
Goosen, Andre,Marais, Charles F.,McCleland, Cedric W.,Rinaldi, Fabrizio C.
, p. 1227 - 1236 (2007/10/02)
A strategy for comparing the 1,5- and 1,6-cyclisation reactions of 3-phenylpropan-1-oxyl radicals is described.Iron(II)-catalysed reduction of 3-(p-methylphenyl)prop-1-yl hydroperoxide and its para-chloro and para-methoxy-substituted analogues, carried out in the presence of copper(II), has been found to give in each case the appropriate para-substituted 3-phenylpropan-1-ol, 3-phenylpropanal and a low yield of a mixture of isomeric 6- and 7-substituted chromans.The alcohols are proposed to form via reduction of either the hydroperoxide or the resulting alkoxyl radical or its cyclised intermediates, and the aldehydes as a result of rearrangement of the alkoxyl radical to an α-hydroxy alkyl radical which subsequently undergoes oxidation.The 7-substituted chromans, which arise directly from 1,6-cyclisation of the alkoxyl radical, were found to dominate the 6-substituted isomers which result from rearrangement of 1,5-cyclised intermediates.This effect is attributed to inefficient interception of the 1,5-cyclised radical intermediate which permits equilibration to the thermodynamically more stable 1,6-cyclised radical isomer to occur.The effect of pH on the reactions has been investigated and although no products typical of the intermediacy of aryl radical cations were detected (even under highly acidic conditions), the formation of such intermediates cannot be excluded.Semiempirical MO calculations have been carried out (at the PM3 level of approximation) on a series of model compounds, yielding results which have clarified our understanding of the effect of substituents on the stabilities of the various intermediates arising from the cyclisation reactions of 3-phenylpropan-1-oxyl radicals.Furthermore, these calculations have supported our assumptions regarding the probability and specificity of rearrangements of the spirodienyl intermediates.
Cyclisation of 3-(p-Methylphenyl)propan-1-ol via its Alkoxyl Radical and Aryl Radical Cation Intermediates. A Comparison of Regioselectivities
Goosen, Andre,McCleland, Cedric W.,Rinaldi, Fabrizio C.
, p. 279 - 281 (2007/10/02)
Evidence is presented that 3-(p-methylphenyl)propan-1-ol 5 undergoes competing 1,5- and 1,6-cyclisation via both its aryl radical cation 6 and alkoxy radical 7 intermediates.Variations in both product yields and regioselectivities of cyclisation with pH are observed, with evidence of significant differences between the two intermediates.
Synthetic and Stereochemical Studies of the Octahydro-1-benzopyran System
Griffiths, D. Vaughan,Wilcox, Geoffrey
, p. 431 - 436 (2007/10/02)
The cis and trans isomers of the octahydro-1-benzopyran system have been synthesised and their conformations studied by low-temperature (13)C and highfield (1)H n.m.r. spectroscopy.The position of the conformational equilibrium in the cis isomer at -70 deg C in CDCl3-CFCl3 (50:50) has been determined as approximately 99.5:0.5 (ΔG0 -8.9 kJ mol-1) in favour of the conformation having the oxygen axially disposed towards the cyclohexane ring.
Oxygen Heterocycles by the Parham Cyclialkylation
Bradsher, Charles K.,Reames, David C.
, p. 1384 - 1388 (2007/10/02)
The addition of butyllithium at -100 deg C to ω-bromoalkyl ethers of o-bromophenol (and its congeners) led to preferential exchange of the aryl bromine at position 2.The resulting organolithium reagents, under suitable conditions, cyclized to afford 2,3-dihydrobenzofurans (6), 3,4-dihydro-2H-1-benzopyrans (13), or 2,3,4,5-tetrahydro-1-benzoxepins (16) in good yields, but less satisfactory results were obtained with the intermediate expected to produce 8-methyl-3,4,5,6-tetrahydro-2H-1-benzoxocin (19). ω-Bromoethyl and ω-bromopropyl ethers of suitable dibromophenols were treated successively with 2 equiv of butyllithium and an electrophile to yield derivatives of 6 and 13.
