Enantio- and Diastereo-Selective Synthesis of (+)-Grandisol

Narasaka, Koichi; Kusama, Hiroyuki; Hayashi, Yujiro

doi:10.1246/bcsj.64.1471

Cited by 41 publications

(32 citation statements)

References 29 publications

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“…Melting points were determined on a Reichert hotstage apparatus and are uncorrected. Al(ClO 4 ) 3 , [48] Cu(CH 3 CN) 4 PF 6 , [49] Bi(OTf) 3 [50] and compounds 2 a, [51] 2 g, [52] 2 h [53] and 2 i, [54] were prepared according to literature procedures. V(ClO 4 ) 3 ¥n H 2 O was prepared in situ from VCl 3 and AgClO 4 ¥H 2 O.…”

Section: Methodsmentioning

confidence: 99%

Evidence That Protons Can Be the Active Catalysts in Lewis Acid Mediated Hetero‐Michael Addition Reactions

Wabnitz

Spencer

2004

Chemistry A European J

324

169

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The mechanism of Lewis acid catalysed hetero-Michael addition reactions of weakly basic nucleophiles to alpha,beta-unsaturated ketones was investigated. Protons, rather than metal ions, were identified as the active catalysts. Other mechanisms have been ruled out by analyses of side products and of stoichiometric enone-catalyst mixtures and by the use of radical inhibitors. No evidence for the involvement of pi-olefin-metal complexes or for carbonyl-metal-ion interactions was obtained. The reactions did not proceed in the presence of the non-coordinating base 2,6-di-tert-butylpyridine. An excellent correlation of catalytic activities with cation hydrolysis constants was obtained. Different reactivities of mono- and dicarbonyl substrates have been rationalised. A (1)H NMR probe for the assessment of proton generation was established and Lewis acids have been classified according to their propensity to hydrolyse in organic solvents. Brønsted acid-catalysed conjugate addition reactions of nitrogen, oxygen, sulfur and carbon nucleophiles are developed and implications for asymmetric Lewis acid catalysis are discussed.

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Section: Methodsmentioning

confidence: 99%

Evidence That Protons Can Be the Active Catalysts in Lewis Acid Mediated Hetero‐Michael Addition Reactions

Wabnitz

Spencer

2004

Chemistry A European J

324

169

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“…Chiral synthesis of (+)‐ 2 has received considerable attention because of its simple but unique cyclobutane structure possessing condensed methyl, hydroxyethyl, and isopropenyl groups. A literature survey for the chiral total syntheses of (+)‐ 2 revealed 13 examples, categorized into (i) standard optical resolution and kinetic resolution methods, (ii) transformations of natural and unnatural chiral pools, and (iii) utilization of catalytic asymmetric cycloaddition starting from achiral olefins …”

Section: Resultsmentioning

confidence: 99%

Ring‐Closing Strategy Utilizing Nitrile α‐Anions: Chiral Synthesis of (+)‐Norchrysanthemic Acid and Expeditious Asymmetric Total Synthesis of (+)‐Grandisol

et al. 2018

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Chiral syntheses of two distinct small cycloalkanes, (1R,3R)‐(1Z)‐norchrysanthemic acid and (+)‐grandisol, were performed by characteristic ring‐closing methodologies using carbanions at the α‐position of nitriles (nitrile α‐anions). (i) (1R,3R)‐(1Z)‐Norchrysanthemic acid, a highly potent ingredient of synthetic pyrethroid containing a cyclopropane structure, was synthesized from readily available (S)‐epoxide derived from 3‐methyl‐but‐2‐en‐1‐ol in 7 steps in 23 % overall yield and with > 98 % ee. This sequence involves a trans‐selective cyclopropane formation using the nitrile α‐anion of (S)‐3‐mesyloxynitrile as the key step. The present chiral synthesis was performed with effective stereocontrol of both the chirality in the 1,3‐positions on the cyclopropane and the Z‐geometry of the propenyl group. (ii) (+)‐Grandisol, an insect sex pheromone possessing a characteristic cyclobutane structure, was synthesized from commercially available cyclopropyl methyl ketone (route A) or from commercially available 3‐cyanopropylzinc bromide and 1‐bromo‐1‐methylpropene (route B) in 10 or 8 steps in 6 % or 8 % overall yield and with 80 % ee. This sequence involves a Shi asymmetric epoxidation of a trisubstituted olefin and a straightforward Stork‐type asymmetric cyclobutane formation with clean SN2 stereoinversion using the nitrile α‐anion of the chiral epoxynitrile. The present expedient method is the second asymmetric total synthesis starting from achiral compounds.

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“…[27] Theprocess employed aTi-TADDOL catalyst [TiCl 2 (OiPr) 2 + 67]w hich allowed reaction of unsaturated oxazolidinones (58)a nd alkenyl (59, 63), allenyl (62), and alkynyl sulfides (61)w ith excellent levels of enantioselectivity. [27,28] Either unsubstituted or ester-substituted, unsaturated oxazolidinones were necessary for high levels of reactivity. Reactions with cyclic alkenyl sulfides (63)o ra llenyl sulfides (62)a re particularly impressive as high levels of diastereoselectivity and enantioselectivity were observed.…”

Section: Sigma Lewis Acids:stepwise Reactionsmentioning

confidence: 99%

Cyclobutane and Cyclobutene Synthesis: Catalytic Enantioselective [2+2] Cycloadditions

2015

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Cyclobutanes and cyclobutenes are important structural motifs found in numerous biologically significant molecules, and they are useful intermediates for chemical synthesis. Consequently, [2+2] cycloadditions to access cyclobutanes and cyclobutenes have been established to be particularly useful transformations. Within the last 10 years, an increase in the frequency of publications for catalytic enantioselective [2+2] cycloadditions has occurred. These reactions provide access to a wide array of enantiomerically enriched chemical diversity that was not previously attainable. Described in this review are the advances made in catalytic enantioselective [2+2] cycloadditions to access cyclobutanes and cyclobutenes.

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Enantio- and Diastereo-Selective Synthesis of (+)-Grandisol

Cited by 41 publications

References 29 publications

Evidence That Protons Can Be the Active Catalysts in Lewis Acid Mediated Hetero‐Michael Addition Reactions

Evidence That Protons Can Be the Active Catalysts in Lewis Acid Mediated Hetero‐Michael Addition Reactions

Ring‐Closing Strategy Utilizing Nitrile α‐Anions: Chiral Synthesis of (+)‐Norchrysanthemic Acid and Expeditious Asymmetric Total Synthesis of (+)‐Grandisol

Cyclobutane and Cyclobutene Synthesis: Catalytic Enantioselective [2+2] Cycloadditions

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