Synthesis and diels-alder reactions of (R)-4-hydroxy-4-p-tolylsulfinylmethyl-2,5-cyclohexadienone

Carreño, M. Carmen; González, Manuel Pérez; Fischer, Jean

doi:10.1016/0040-4039(95)00879-h

Cited by 14 publications

(25 citation statements)

References 27 publications

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“…(SS)-[(p-Tolylsulfinyl)methyl]-p-quinol (9) was synthesized following the procedure reported for the (SR)-enantiomer, [25] by reaction of 4,4-dimethoxy-2,5-cyclohexadienone (11) with the lithium anion derived from (SS)-methyl-p-tolylsulfoxide 12, [26] followed by ketal hydrolysis with aqueous oxalic acid, in 76 % overall yield. The stereoselective conjugated addition of AlMe 3 on 9 was conducted successfully after an optimization study (Scheme 2, Table 1).…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis of Rubiginones A₂ and C₂ and Their 11‐Methoxy Regioisomers

Carreño

Somoza

Ribagorda

et al. 2007

Chemistry A European J

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Convergent enantioselective syntheses of angucyclinone-type natural products rubiginones A(2) (2) and C(2) (1) and their 11-methoxy regioisomers 3 a and 3 b have been achieved by using two domino processes from a common enantiomerically pure 1-vinylcyclohexene 4. Key steps in the synthesis of this diene were the stereoselective conjugate addition of AlMe(3) on (SS)-[(p-tolylsulfinyl)methyl]-p-quinol (9) and the elimination of the beta-hydroxy sulfoxide fragment, after oxidation to sulfone, to recover a carbonyl group. The first domino sequence comprised Diels-Alder reaction with a sulfinyl naphthoquinone followed by sulfoxide elimination. An efficient opposite regioselection in the cycloaddition step was achieved in the convergent construction of the tetracyclic skeleton using a sulfoxide at C-2 or C-3 of the dienophiles 5 or 6, derived from 5-methoxy-1,4-naphthoquinone. The second domino process, triggered by oxygen and sunlight, allowed the transformation of the initial tetracyclic adducts into the final products after B ring aromatization, silyl deprotection and C-1 oxidation.

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Section: Resultsmentioning

confidence: 99%

Asymmetric Synthesis of Rubiginones A₂ and C₂ and Their 11‐Methoxy Regioisomers

Carreño

Somoza

Ribagorda

et al. 2007

Chemistry A European J

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“…The synthesis of enantiopure diene 4 began with 3,3,6,6‐tetramethoxy‐1,4‐cyclohexadiene ( 10 ),23 which was subjected to a controlled monohydrolysis with a mixture of acetone/water 10:1 affording the dimethyl monoketal of p ‐benzoquinone ( 11 )24 in 88 % yield (Scheme 2). (S S )‐[( p ‐Tolylsulfinyl)methyl]‐ p ‐quinol ( 9 ) was synthesized following the procedure reported for the (S R )‐enantiomer,25 by reaction of 4,4‐dimethoxy‐2,5‐cyclohexadienone ( 11 ) with the lithium anion derived from (S S )‐methyl‐ p ‐tolylsulfoxide 12 ,26 followed by ketal hydrolysis with aqueous oxalic acid, in 76 % overall yield. The stereoselective conjugated addition of AlMe 3 on 9 was conducted successfully after an optimization study (Scheme 2, Table 1).…”

Section: Resultsmentioning

confidence: 99%

OC022: Quality control in the measurement of nuchal translucency in the first trimester of pregnancy

Brogan¹,

Crossley²,

Stenhouse³

et al. 2003

Ultrasound Obstet Gynecol

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Convergent enantioselective syntheses of angucyclinone‐type natural products rubiginones A2 (2) and C2 (1) and their 11‐methoxy regioisomers 3 a and 3 b have been achieved by using two domino processes from a common enantiomerically pure 1‐vinylcyclohexene 4. Key steps in the synthesis of this diene were the stereoselective conjugate addition of AlMe3 on (SS)‐[(p‐tolylsulfinyl)methyl]‐p‐quinol (9) and the elimination of the β‐hydroxy sulfoxide fragment, after oxidation to sulfone, to recover a carbonyl group. The first domino sequence comprised Diels–Alder reaction with a sulfinyl naphthoquinone followed by sulfoxide elimination. An efficient opposite regioselection in the cycloaddition step was achieved in the convergent construction of the tetracyclic skeleton using a sulfoxide at C‐2 or C‐3 of the dienophiles 5 or 6, derived from 5‐methoxy‐1,4‐naphthoquinone. The second domino process, triggered by oxygen and sunlight, allowed the transformation of the initial tetracyclic adducts into the final products after B ring aromatization, silyl deprotection and C‐1 oxidation.

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“…54 Shortly thereafter, the group described the diastereoselective addition of organoalanes (AlR 3 ) into the cyclohexadienone core of enantiopure sulfoxide 182 (Scheme 34). 55 In all cases, product 183 was isolated as a single diastereomer.…”

Section: Desymmetrization Using Internal Asymmetric Inductionmentioning

confidence: 99%

Asymmetric transformations of achiral 2,5-cyclohexadienones

2014

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Cyclohexadienones are versatile platforms for performing asymmetric synthesis as evidenced by the numerous natural product syntheses that exploit their diverse reactivity profile. However, there are few general methods available for the direct asymmetric synthesis of chiral cyclohexadienones. To circumvent this problem, several researchers have developed catalytic asymmetric methods that employ readily available achiral 2,5-cyclohexadienones as substrates. Many of these reactions are desymmetrizations in which one of the enantiotopic alkenes of an achiral dienone is transformed. Others involve selective reaction at one alkene of an unsymmetrically substituted, achiral dienone. This review will cover advances in this area over the last 20 years and the application of these strategies in complex molecule synthesis.

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Synthesis and diels-alder reactions of (R)-4-hydroxy-4-p-tolylsulfinylmethyl-2,5-cyclohexadienone

Cited by 14 publications

References 27 publications

Asymmetric Synthesis of Rubiginones A₂ and C₂ and Their 11‐Methoxy Regioisomers

Asymmetric Synthesis of Rubiginones A₂ and C₂ and Their 11‐Methoxy Regioisomers

OC022: Quality control in the measurement of nuchal translucency in the first trimester of pregnancy

Asymmetric transformations of achiral 2,5-cyclohexadienones

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Synthesis and diels-alder reactions of (R)-4-hydroxy-4-p-tolylsulfinylmethyl-2,5-cyclohexadienone

Cited by 14 publications

References 27 publications

Asymmetric Synthesis of Rubiginones A2 and C2 and Their 11‐Methoxy Regioisomers

Asymmetric Synthesis of Rubiginones A2 and C2 and Their 11‐Methoxy Regioisomers

OC022: Quality control in the measurement of nuchal translucency in the first trimester of pregnancy

Asymmetric transformations of achiral 2,5-cyclohexadienones

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Asymmetric Synthesis of Rubiginones A₂ and C₂ and Their 11‐Methoxy Regioisomers

Asymmetric Synthesis of Rubiginones A₂ and C₂ and Their 11‐Methoxy Regioisomers