- Dialkoxycarbenes in (4 + 1) Cycloadditions: Application to the Synthesis of Carotol
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Dialkoxycarbenes are more reactive than NHCs and participate in many reactions including a formal (4 + 1) cycloaddition with electron-deficient dienes. We have learned to control the relative stereochemistry of the newly created chiral carbons in this pro
- Gund, MacHhindra,Déry, Martin,Amzallag, Valérie,Spino, Claude
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supporting information
p. 4280 - 4283
(2016/10/31)
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- Enantioselective formal synthesis of eurylene: Synthesis of the cis - And trans -THF fragments using oxidative cyclization
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A formal synthesis of eurylene is described, where both cis- and trans-THF-containing fragments were prepared using diastereo- and chemoselective permanganate-mediated oxidative monocyclizations of trienes.
- Sheikh, Nadeem S.,Bataille, Carole J.,Luker, Tim J.,Brown, Richard C. D.
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supporting information; experimental part
p. 2468 - 2471
(2010/07/05)
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- Asymmetric synthesis of dienomycin C
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The first asymmetric synthesis of dienomycin C was accomplished in seven Steps and 46% overall yield.
- Comins,Green
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p. 217 - 218
(2007/10/03)
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- Chiral auxiliary mediated pictet-spengler reactions: Asymmetric syntheses of (-)-laudanosine, (+)-glaucine and (-)-xylopinine
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Cyclohexyl-based chiral auxiliaries can be used effectively in an asymmetric Pictet-Spengler synthesis of tetrahydroisoquinoline, aporphine and protoberbine alkaloids. Using this strategy, concise asymmetric syntheses of (-)-laudanosine, (+)-glaucine and (+)- xylopinine have been accomplished.
- Comins, Daniel L.,Thakker, Paresh M.,Baevsky, Matthew F.,Badawi, Mohamed M.
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p. 16327 - 16340
(2007/10/03)
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- An efficient preparation of (+)-trans-2-(α-cumyl)cyclohexanol ((+)-TCC): A practical alternative to (+)-8-phenylmenthol
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An efficient synthesis and resolution of trans-2-(α-cumyl)cyclohexanol gives the (+)-enantiomer in three steps from cyclohexene oxide.
- Comins,Salvador
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p. 801 - 804
(2007/10/02)
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- Efficient Synthesis and Resolution of trans-2-(1-Aryl-1-methylethyl)cyclohexanols; Practical Alternatives to 8-Phenylmenthol
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A short synthesis and resolution of effective chiral auxiliaries of the 8-arylmenthol-type achieved using inexpensive materials, a recyclable lipase, and easily applied procedures that are amenable to large-scale preparation.A variety of isopropylarenes were α-metalated with n-butylithium/potassium tert-pentoxide and treated with cyclohexene oxide to provide racemic trans-2-(1-aryl-1-methylethyl)cyclohexanols 6a-f in fair to high yield.Candida rugosa lipase and lauric acid were used to resolve these racemic alcohols by converting the (-)-enantiomer to its laurateester.The enzymatic resolutions were carried out at 40 deg C and were faster in cyclohexane than in hexanes.The synthesis and resolution of racemic trans-2-(1-methyl-1-phenylethyl)cyclohexanol (6a) were performed on a 1 mol scale in 68 percent overall yield, requiring three steps for (+)-6a and five steps for (-)-6a.
- Comins, Daniel L.,Salvador James M.
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p. 4656 - 4661
(2007/10/02)
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- Cycloalkyl-based chiral auxiliaries and method making the same
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A process of synthesizing enantiomerically pure compounds defined by Formula V, STR1 which are useful as chiral auxiliaries is disclosed. The process comprises, first, combining a base of Formula Y- Z+ (Formula I), wherein Y- is an organic anion and Z+ is an inorganic cation, with a compound of Formula II, STR2 wherein R1 is a C1 -C4 alkyl group and R2 is the same as R1, or wherein R1 and R2 together form cyclopentane or cyclohexane, and wherein R3 is a substituted or unsubstituted aryl group, to form a compound defined by Formula III, STR3 then: (b) reacting the compound of Formula III with a cyclic epoxide defined by Formula IV, STR4 wherein n is 1, 2, or 3, to form a racemic mixture of a compound defined by Formula V. STR5 In a preferred embodiment, the method further comprises stereospecifically esterifying one of the enantiomers of the racemic mixture of compound (V) and a carboxylic acid with an enzyme in an organic solvent, wherein said acid is a C2 -C20 alkyl acid, benzoic acid or a C2 -C14 alkyl benzoic acid, and then separating the esterified enantiomer from the non-esterified enantiomer.
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