A trifluoromethyl group directed semipinacol rearrangement: synthesis of α-(trifluoroacetyl) diarylmethanes

Hornyák, Gyula; Fetter, J.; Németh, Gábor; Poszávácz, László; Simig, Gyula

doi:10.1016/s0022-1139(97)00031-6

Cited by 8 publications

(6 citation statements)

References 4 publications

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“…In both cases,t he yield of the ketone was low.I n fact, the main component of the latter reaction was spirocyclic epoxide 13,formed in 66 %. Tr ifluoromethyl carbinol 5r was tested and as expected, [19] exclusive migration of the Ph group was observed. This substrate was substantially less reactive than the others,r equiring 0 8 8Ct ot rigger the semipinacol rearrangement.…”

Section: Chemiesupporting

confidence: 63%

Divergent, Strain‐Release Reactions of Azabicyclo[1.1.0]butyl Carbinols: Semipinacol or Spiroepoxy Azetidine Formation

2021

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The azetidine moiety is ap rivileged motif in medicinal chemistry and new methods that access them efficiently are highly sought after.T owards this goal, we have found that azabicyclo[1.1.0]butyl carbinols,r eadily obtained from the highly strained azabicyclo[1.1.0]butane (ABB), can undergo divergent strain-release reactions upon N-activation. Treatment with trifluoroacetic anhydride or triflic anhydride triggered as emipinacol rearrangement to give keto 1,3,3substituted azetidines.M ore than 20 examples were explored, enabling us to evaluate selectivity and the migratory aptitude of different groups.A lternatively,t reatment of the same alcohols with benzyl chloroformate in the presence of NaI led to iodohydrin intermediates whichg ave spiroepoxya zetidines upon treatment with base.T he electronic nature of the activating agent dictates whichp athwayoperates.

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Section: Chemiesupporting

confidence: 63%

Divergent, Strain‐Release Reactions of Azabicyclo[1.1.0]butyl Carbinols: Semipinacol or Spiroepoxy Azetidine Formation

2021

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“…Forschungsartikel fact, the main component of the latter reaction was spirocyclic epoxide 13,formed in 66 %. Tr ifluoromethyl carbinol 5r was tested and as expected, [19] exclusive migration of the Ph group was observed. This substrate was substantially less reactive than the others,r equiring 0 8 8Ct ot rigger the semipinacol rearrangement.…”

Section: Angewandte Chemiesupporting

confidence: 63%

Divergent, Strain‐Release Reactions of Azabicyclo[1.1.0]butyl Carbinols: Semipinacol or Spiroepoxy Azetidine Formation

2021

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The azetidine moiety is a privileged motif in medicinal chemistry and new methods that access them efficiently are highly sought after. Towards this goal, we have found that azabicyclo[1.1.0]butyl carbinols, readily obtained from the highly strained azabicyclo[1.1.0]butane (ABB), can undergo divergent strain‐release reactions upon N‐activation. Treatment with trifluoroacetic anhydride or triflic anhydride triggered a semipinacol rearrangement to give keto 1,3,3‐substituted azetidines. More than 20 examples were explored, enabling us to evaluate selectivity and the migratory aptitude of different groups. Alternatively, treatment of the same alcohols with benzyl chloroformate in the presence of NaI led to iodohydrin intermediates which gave spiroepoxy azetidines upon treatment with base. The electronic nature of the activating agent dictates which pathway operates.

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“…[9b-g, 10a] In contrast to Tsuji-Wacker conditions, which proved unreactive towards these electron-deficient internal alkenes, [10] our recently reported procedure for the Wackertype oxidation of internal alkenes resulted in good conversions and excellent regioselectivities. 20:1 (distal oxidation over proximal oxidation) were obtained and further establish the previously unprecedented [13] powerful directing effect of the trifluoromethyl group in Wacker-type oxidations of internal alkenes. [11] Under these conditions, a variety of alkenes bearing allylic trifluoromethyl groups could be oxidized in 70-91 % yield.…”

supporting

confidence: 59%

“…In all cases, selectivities of ! 20:1 (distal oxidation over proximal oxidation) were obtained and further establish the previously unprecedented [13] powerful directing effect of the trifluoromethyl group in Wacker-type oxidations of internal alkenes.…”

mentioning

confidence: 87%

Rapid Access to β‐Trifluoromethyl‐Substituted Ketones: Harnessing Inductive Effects in Wacker‐Type Oxidations of Internal Alkenes

et al. 2014

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We present a practical trifluoromethyl-directed Wacker-type oxidation of internal alkenes that enables rapid access to b-trifluoromethyl-substituted ketones. Allylic trifluoromethyl-substituted alkenes bearing a wide range of functional groups can be oxidized in high yield and regioselectivity. The distance dependence of the regioselectivity was established by systematic variation of the number of methylene units between the double bond and the trifluoromethyl group. The regioselectivity enforced by traditional directing groups could even be reversed by introduction of a competing trifluoromethyl group. Besides being a new powerful synthetic method to prepare fluorinated molecules, this work directly probes the role of inductive effects on nucleopalladation events. Scheme 1. Regiocontrol in Wacker oxidations of internal alkenes. BQ = p-benzoquinone.

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A trifluoromethyl group directed semipinacol rearrangement: synthesis of α-(trifluoroacetyl) diarylmethanes

Cited by 8 publications

References 4 publications

Divergent, Strain‐Release Reactions of Azabicyclo[1.1.0]butyl Carbinols: Semipinacol or Spiroepoxy Azetidine Formation

Divergent, Strain‐Release Reactions of Azabicyclo[1.1.0]butyl Carbinols: Semipinacol or Spiroepoxy Azetidine Formation

Divergent, Strain‐Release Reactions of Azabicyclo[1.1.0]butyl Carbinols: Semipinacol or Spiroepoxy Azetidine Formation

Rapid Access to β‐Trifluoromethyl‐Substituted Ketones: Harnessing Inductive Effects in Wacker‐Type Oxidations of Internal Alkenes

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