Regioselective hydroxysulphenylation of derivatives of allylicalcohols and amines

Samii, Z. K. M. Abd El; Ashmawy, M. I. Al; Mellor, John M.

doi:10.1016/s0040-4039(00)85193-x

Cited by 13 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An addition of Cu(OAc) 2 to the reaction with 2b using Pd(OAc) 2 resulted in rather suppressed yields of 3b and 4b (Tables 1 and 4). The use of Cu(OAc) 2 , Mn(OAc) 3 or Pb(OAc) 4 instead of Pd(OAc) 2 in the reaction with 2b did not yield the products 3b and 4b (Table 4); Cu(OAc) 2 forms a complex with the alkene, and thus it would not operate as oxidizing agent. Mn(OAc) 3 is not effective since it oxidizes AcOH [16].…”

Section: Effects Of Oxidantsmentioning

confidence: 99%

“…Mn(OAc) 3 is not effective since it oxidizes AcOH [16]. Pb(OAc) 4 is too strong an oxidant to be effective, giving a lot of unidentified products. PdSO 4 is difficult to dissolve in AcOH, so that it could scarcely be effective.…”

Section: Effects Of Oxidantsmentioning

confidence: 99%

“…Since AgOAc is complexed with alkene, it would be not so effective for the reaction. 3 2.4 0 0 -Pb(OAc) 4 2.4 0 0 -a The yields are calculated to be 100% when two moles of product are formed from one mole Pd(OAc) 2 or Cu(OAc) 2 and from two moles AgOAc. b Pd(OAc) 2 (0.60 mmol) and Cu(OAc) 2 (3.6 mmol) were used, and the yields are obtained on the basis of Pd(OAc) 2 .…”

Section: Effects Of Oxidantsmentioning

confidence: 99%

“…Thiiranium ion intermediates have been generated by reactions of disulfides with alkenes in the presence of oxidants such as Pb(OAc) 4 [1][2][3][4], Mn(OAc) 3 [2][3][4], Fe(OAc) 3 [2][3][4] or Cu(OAc) 2 [5], by reactions of β-thiohalides with AgY [6] and by reactions of thiiranes with RY [6]. The intermediates which have soft counterions such as BF 4 − , PF 6 − , SbF 6 − , SbCl 5 − , FSO 3 − and CF 3 CO 2 − behave like carbenium ions [1] of a weakly bridged strong electrophile, undergoing a rapid ring-opening by the outer nucleophile at low temperature (−20-0 o C) to give the observed predominant Markovnikov regioselectivity; in some cases, the skeletal rearrangement or stereoconversion of the thiiranium ions has been observed.…”

Section: Introductionmentioning

confidence: 99%

“…The intermediates which have soft counterions such as BF 4 − , PF 6 − , SbF 6 − , SbCl 5 − , FSO 3 − and CF 3 CO 2 − behave like carbenium ions [1] of a weakly bridged strong electrophile, undergoing a rapid ring-opening by the outer nucleophile at low temperature (−20-0 o C) to give the observed predominant Markovnikov regioselectivity; in some cases, the skeletal rearrangement or stereoconversion of the thiiranium ions has been observed. We may infer that the reactions of RSCl with alkenes would generate not a σ-sulfurane but a strongly bridged thiiranium ion pairing tightly with hard Cl − [1], and thus the ring-opening by the pairing Cl − leads to the anti-Markovnikov regioselectivity without undergoing the stereoconversion and skeletal rearrangement.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Novel Behavior of Thiiranium Radical Cation Intermediates. Reactions of Dimethyl Disulfide with Alkenes in the Presence of Pd(OAc)2

2000

View full text Add to dashboard Cite

Reaction of dimethyl disulfide (1) with cyclohexene (2a) in AcOH in the presence of Pd(OAc) 2 yields trans-1-acetoxy-2-methylcyclohexane (3a). The equivalent reactions with hex-1-ene (2b) and 2-methylpent-1-ene (2c) or 1-methylcyclohex-1-ene (2d) preferentially give anti-Markovnikov and Markovnikov adducts 4 and 3, respectively, by acetoxymethylthiolation of the alkene. The Markovnikov regioselectivity 3b/4b for the reaction with 2b is higher than that for the reaction using AgOAc instead of Pd(OAc) 2, which proceeds via a thiiranium ion. Addition of a polar solvent (MeCN or MeNO 2 ) to the reactions with 2b or 2c using Pd(OAc) 2 abnormally decreases the Markovnikov regioselectivity. The total yield of 3 and 4 increases with an increased concentration of AcOH. Compounds 3 and 4 are also formed and the reactions in MeCN or MeNO 2 not containing AcOH. A solution of Pd(OAc) 2 in 1 exhibits λ max 380 nm (log ε 3.6) assigned to the absorption of a relatively stable sulfonium salt. These indicate that the reactions using Pd(OAc) 2 proceed by S N 2 ringopening of a new type of thiiranium radical cations paired with − OAc via the sulfonium salts. The insensitivity of the 3/4 ratios to the reaction time at 25-60°C in the reactions with 2c-d shows the ring-opening to be controlled kinetically, but the increased ratio with reaction time at 116°C in the reaction with 2b suggests that the ring-opening is thermodynamically governed. The reaction product with 2d also undergoes a skeletal rearrangement to a thietanium radical cation to give 1-acetoxymethyl-2-methylthiocyclohexane.

show abstract