Michael, Michael–aldol and Michael–Michael reactions of enolate equivalents of butane-2,3-diacetal protected glycolic acid derivatives

Ley, Steven V.; Dixon, Darren J.; Guy, Richard T.; Rodríguez, Félix; Sheppard, Tom D.

doi:10.1039/b512410g

Cited by 26 publications

(6 citation statements)

References 64 publications

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“…22 Consequently, enantiopure cyclopentenone 29 , which is readily available in 4 steps from cyclopentadiene, was used as the Michael acceptor. 23 The union of silyl ketene acetal 28 24 and enone 29 to afford cyclopentenone 30 was realized in good yield in dry DMF in the presence of lithium acetate. 25 Earlier attempts to promote this reaction with Lewis acids (SnCl 4 or TiCl 4 in CH 2 Cl 2 ) or tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) were less successful.…”

Section: Resultsmentioning

confidence: 99%

Divergent Synthesis and Chemical Reactivity of Bicyclic Lactone Fragments of Complex Rearranged Spongian Diterpenes

et al. 2011

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The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described (Schemes 2–5). In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed (Scheme 6). Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group—in either the bridged or fused series—is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E.

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Section: Resultsmentioning

confidence: 99%

Divergent Synthesis and Chemical Reactivity of Bicyclic Lactone Fragments of Complex Rearranged Spongian Diterpenes

et al. 2011

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“…Ley and co-authors also explored the Michael-aldol and Michael-Michael reactions to give multi-functional benzopyranones with high diastereoselectivity. 89 They also examined the further applicability of the benzopyranone 74 by reducing it with RaneyNi; the lactone underwent spontaneous ring-opening, forming γ -lactam 75 after the usual methanolysis. This demonstrated the potential of this methodology to deliver highly functionalized single enantiomers from simple starting materials (Scheme 20).…”

Section: Scheme 19mentioning

confidence: 99%

Syntheses and Biological Activities of Chroman-2-ones. A Review

Kamat

Tilve

Kamat

et al. 2015

Organic Preparations and Procedures International

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“…compounds (S,S)-and (R,R)-125 (Scheme 21), that have a rigid chair conformation and induce excellent diastereoselectivities in a wide range of reactions, from alkylations with alkyl halides, 62,63 aldol reactions with aldehydes, 64 ketones 65 or acid chlorides, 66 Michael additions, 67 Michael-aldol reactions 68 and Michael-Michael additions. 68,69 For instance, an efficient synthesis of enantiopure a-aryl-a-hydroxy esters (S)-and (R)-128 was achieved from diacetals (R,R)-and (S,S)-125, respectively, by diastereoselective palladium-catalyzed a-arylation reactions of the corresponding silylenol ether 126 (Scheme 22). 70…”

Section: Bda-protected Glycolic Derivativesmentioning

confidence: 99%

The conformational rigidity of butane-1,2-diacetals as a powerful synthetic tool

2008

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Butane-1,2-diacetals are selective protecting groups for trans-diequatorial-1,2-diols and have been widely used in carbohydrate chemistry. The scope of diacetal protection has been extended more recently to include other important hydroxylated chiral templates containing trans-1,2-diols, such as quinic and shikimic acids, the protection of which as diacetals leads to a strong conformational rigidity that induces excellent diastereoselectivity control. In addition, the chiral information stored in the diacetal backbone has also been exploited in the synthesis of important building blocks, such as glycerate, glycolate and tartrate diacetal derivatives. In this critical review, the synthetic power of the conformational rigidity and the chirality stored in the diacetal backbone is described. This phenomenon will be illustrated with recent examples of applications in the synthesis of natural products or biologically interesting compounds (80 references).

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Michael, Michael–aldol and Michael–Michael reactions of enolate equivalents of butane-2,3-diacetal protected glycolic acid derivatives

Abstract: Consecutive coupling reactions of butane-2,3-diacetal protected glycolic acid derivatives with Michael acceptors and aldehydes are reported. An enantiopure sample of this building block was used to kinetically resolve a chiral Michael acceptor present as a racemic mixture of enantiomers.

Cited by 26 publications

References 64 publications

Divergent Synthesis and Chemical Reactivity of Bicyclic Lactone Fragments of Complex Rearranged Spongian Diterpenes

Divergent Synthesis and Chemical Reactivity of Bicyclic Lactone Fragments of Complex Rearranged Spongian Diterpenes

Syntheses and Biological Activities of Chroman-2-ones. A Review

The conformational rigidity of butane-1,2-diacetals as a powerful synthetic tool

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