A Convergent Approach to (−)‐Callystatin A Based on Local Symmetry

Candy, Mathieu; Tomas, Loïc; Parat, Sabrina; Héran, Virginie; Bienaymé, Hugues; Pons, Jordi; Bressy, Cyril

doi:10.1002/chem.201202701

Cited by 21 publications

(13 citation statements)

References 61 publications

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“…Its s value (27 for 1t)w as quite similar to the unsaturated precursor 1o(s = 29). [18] This hiddensymmetry strategy [19] represents the shortest synthesis of this target reported to date. We decided to apply this methodology to the total synthesis of (+ +)-cryptocaryalactone, [15] anatural germination inhibitor (Scheme 5).…”

Section: Angewandte Chemiementioning

confidence: 99%

Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti‐1,3‐Diols: The Additive Horeau Amplification

Merad

Borkar

Caïjo³

et al. 2017

Angewandte Chemie

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The concept of asynergistic double catalytic kinetic resolution (DoCKR) as described in this article was successfully applied to racemic acyclic anti-1,3-diols,acommon motif in natural products.This process takes advantage of an additive Horeau amplification involving two successive enantioselective organocatalytic acylation reactions,a nd leads to diesters and recovered diols with high enantiopurities.Itwas first developed with C 2 -symmetrical diols and then further extended to non-C 2symmetrical anti diols to prepare useful chiral building blocks. The protocol is highly practical as it only requires 1mol %o f ac ommercially available organocatalyst and leads to easily separable products.This procedure was applied to the shortest reported total synthesis of (+ +)-cryptocaryalactone,an atural product with anti-germinative activity.How can one improve the enantioselectivity outcome of ar eaction on aw ide scope?T his question arises during the development of any given catalytic enantioselective transformation. Theindispensable optimization stage improves the enantiomeric ratio (e.r.) of ar eaction through the variations of the chemical and/or physical parameters of the transformation. Usually,e .r. enhancement is rapidly accompanied by an arrowing of the reaction scope.M ost of the time,t he rational design of the catalyst structure is the only option to improve reactivity and selectivity.T his fine-tuning is nonetheless time consuming because of the difficulty of considering all the parameters involved in the enantiodetermining transition state,e ven though it can result in negligible improvements.In contrast, the Horeau principle [1] is responsible for the improvement of enantioselectivity in some reactions which rely on polyfunctionalized substrates.Byapplying at least two identical successive enantioselective transformations,t he second reaction can act as an additional stereocontrolling filter to improve the enantiopurity of the final product. Since the pioneering works of Horeau in the 70's, such amplification of enantioselectivity was observed in several catalytic trans-formations. [2,3,5e] In enantioselective catalysis,t he Horeau amplification can be divided into two main categories: 1) In the subtractive Horeau amplification, the minor enantiomer obtained after the first transformation is the substrate of the second transformation. Thep olyfunctionalized substrates involved in this first category are either prochiral [3,4] or meso compounds. [3,5] 2) In the additive Horeau amplification, the major enantiomer formed after the first reaction is rapidly consumed in the second enantioselective (or diastereoselective) transformation. [6] However,i nc ontrast to the subtractive processes,e xamples of additive amplifications involving starting materials with pre-existing stereocenters are extremely scarce (Scheme 1). [7] Although observed many times,the Horeau amplification is still considered an anecdotal phenomenon. By considering the synthetic potential supported by the Horeau principle in enantioselect...

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Section: Angewandte Chemiementioning

confidence: 99%

Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti‐1,3‐Diols: The Additive Horeau Amplification

Merad

Borkar

Caïjo³

et al. 2017

Angewandte Chemie

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“…As oxidants, activated MnO 2 [43][44][45][46], barium permanganate [47,48], tetra-n-propylammonium perruthenate (TPAP)/N-methylmorpholine N-oxide (NMO) [49][50][51][52][53][54] and TPAP/N,N,N′,N′-tetramethylenediamine dioxide (TMEDAO 2 ) [55], o-iodoxybenzoic acid (IBX) [56][57][58], Dess-Martin periodinane [59][60][61], DMSO-oxalyl chloride (Swern conditions) [62][63][64], DMSO-SO 3 -pyridine (Parikh-Doering oxidation) [38,39] or DMSO-SO 3 -triethylamine [65], pyridinium chlorochromate (PCC) or PCC/celite [66][67][68][69] as well as pyridinium dichromate (PDC) [70] such as PDC encapsulated in sol gel [71] (27) [72], nanoparticulate ruthenium supported on highly porous aluminum oxyhydroxide [73] or on silica gel [74], and nickel nanoparticles [75,76] Tandem-, Domino-and One-Pot Reactions Involving Wittig-and Horner-Wadsworth-Emmons... http://dx.doi.org/10.5772/intechopen.70364using activated MnO 2 [79]. Over the years, this process has been used more often [40,[80][81][82]…”

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confidence: 99%

Tandem-, Domino- and One-Pot Reactions Involving Wittig- and Horner-Wadsworth-Emmons Olefination

Merza¹,

Taha²,

Thiemann³

2018

Alkenes

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The Wittig olefination utilizing phosphoranes and the related Horner-WadsworthEmmons (HWE) reaction using phosphonates transform aldehydes and ketones into substituted alkenes. Because of the versatility of the reactions and the compatibility of many functional groups towards the transformations, both Wittig olefination and HWE reactions are a mainstay in the arsenal of organic synthesis. Here, an overview is given on Wittig-and Horner-Wadsworth-Emmons (HWE) reactions run in combination with other transformations in one-pot procedures. The focus lies on one-pot oxidation Wittig/HWE protocols, Wittig/HWE olefinations run in concert with metal catalyzed cross-coupling reactions, Domino Wittig/HWE-cycloaddition and Wittig-Michael transformations.

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“…Migration of the internal double bond under DBU catalysis [17] and subsequent acylation reaction afforded (+ +)-cryptocaryalactone. [18] This hiddensymmetry strategy [19] represents the shortest synthesis of this target reported to date. [20] Additionally, no protecting group was required for this synthesis, [21] which involved a unique organocatalytic enantioselective step.…”

mentioning

confidence: 99%

Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti‐1,3‐Diols: The Additive Horeau Amplification

Merad

Borkar

Caïjo³

et al. 2017

Angew Chem Int Ed

Self Cite

View full text Add to dashboard Cite

The concept of a synergistic double catalytic kinetic resolution (DoCKR) as described in this article was successfully applied to racemic acyclic anti‐1,3‐diols, a common motif in natural products. This process takes advantage of an additive Horeau amplification involving two successive enantioselective organocatalytic acylation reactions, and leads to diesters and recovered diols with high enantiopurities. It was first developed with C2‐symmetrical diols and then further extended to non‐C2‐symmetrical anti diols to prepare useful chiral building blocks. The protocol is highly practical as it only requires 1 mol % of a commercially available organocatalyst and leads to easily separable products. This procedure was applied to the shortest reported total synthesis of (+)‐cryptocaryalactone, a natural product with anti‐germinative activity.

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A Convergent Approach to (−)‐Callystatin A Based on Local Symmetry

Cited by 21 publications

References 61 publications

Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti‐1,3‐Diols: The Additive Horeau Amplification

Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti‐1,3‐Diols: The Additive Horeau Amplification

Tandem-, Domino- and One-Pot Reactions Involving Wittig- and Horner-Wadsworth-Emmons Olefination

Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti‐1,3‐Diols: The Additive Horeau Amplification

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