A concise enantioselective synthesis of (+)-decarestrictine L via proline-catalyzed sequential α-aminooxylation and Horner–Wadsworth–Emmons olefination

Rawat, Varun; Chouthaiwale, Pandurang V.; Suryavanshi, Gurunath; Sudalai, Arumugam

doi:10.1016/j.tetasy.2009.08.026

Cited by 20 publications

(9 citation statements)

References 27 publications

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“…Chiral HPLC analyses were performed with Merck-Hitachi sys- The following substrates were purchased from commercial sources: 1-octene (Acros, distilled prior to use), 4-vinyl-1-cyclohexene (Acros), 5-hexen-1-ol (Merck), 5-hexen-2-one (AlfaAesar), 3,3-dimethyl-1-butene (AlfaAesar), 1,7-octadiene (Acros), ethyl glyoxylate (Aldrich), benzyl carbamate (AlfaAesar), and K 2 HPO 4 (Riedel-de-Haën). The following substrates were prepared according to literature procedures: 6-diphenylphosphanylpyridin-2(1H)one (6-DPPon), 11a tert-butyldimethylundec-10-enyloxysilane, 16 hex-5-enyl acetate, 17 hex-5-enyloxymethylbenzene, 18 2-dec-9enyl [1,3]dioxolane, 19 undec-10-enoic acid methylphenylamide, 20 hex-5-enyl benzoate, 21 tert-butyl carbamate. 22 Ethyl The analytical data correspond to those reported previously.…”

Section: Scheme 1 Design Of a Domino Hydroformylation-aminocatalytic mentioning

confidence: 99%

Tandem Regioselective Rhodium-Catalyzed Hydroformylation–Enantioselective Aminocatalytic anti-Mannich Reaction

Diezel

Breit

2014

Synthesis

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The first tandem regioselective hydroformylation and enantioselective organocatalytic anti-Mannich reaction is reported. Starting from α-olefins, valuable functionalized amino acid derivatives were obtained in excellent yields and with high levels of diastereo-and enantioselectivities. The products represent valuable building blocks for biologically and pharmaceutically interesting targets.Functionalized α-amino acid derivatives are valuable building blocks for the synthesis of target structures of biological and medicinal interest. 1 As such, the development of methods for their preparation has drawn a lot of attention. 2-4 Among the many approaches used to achieve this goal, an elegant process is the organocatalytic Mannich reaction between enolizable aldehydes and imines. 5-7 However, enolizable aldehydes themselves are reactive substrates that may undergo side reactions such as aldol reactions and oligomerization, which can be obstructive for obtaining high yields. One strategy to avoid such undesired side reactions is to generate the aldehyde in a low stationary concentration by way of a catalytic reaction. As we have demonstrated recently, this can be efficiently achieved by generating an aldehyde in situ through the application of atom-economic hydroformylation of alkenes. By applying this strategy, we were able to develop an efficient enantioselective tandem regioselective hydroformylation and organocatalytic enantioselective aldol addition 8 as well as a tandem regioselective hydroformylation-Biginelli reaction. 9,10 We report herein on an extension of this concept with the development of the first tandem regio-, diastereo-and enantioselective hydroformylation-organocatalytic antiMannich reaction.Among the different known methods for organocatalytic Mannich reactions, we were attracted by the anti-selective Mannich methodology developed by Melchiore et al. 7 Central to this method is the generation of N-carbamatesubstituted imines in situ through base-initiated elimination of tolyl sulfinic acid from stable α-amidosulfones 2 (Scheme 1). An interesting aspect of this method is that NBoc or N-Cbz protected α-amino acids are obtained directly, which allows for follow-up peptide construction. Scheme 1 Design of a domino hydroformylation-aminocatalyticanti-Mannich reaction A crucial factor for success of the envisioned tandem hydroformylation-Mannich approach was the selection of the optimal catalyst system for the hydroformylation step. First, the catalyst has to be compatible with the substrates, reagents and the organocatalyst present at the same time. Second, it has to operate under mild conditions to allow for low reaction temperatures to ensure good enantioselectivities in the organocatalytic Mannich step. Finally the enolizable aldehyde reaction partner has to be generated through hydroformylation in high chemo-and regioselectivities.A catalyst system that has the potential to fulfill all these demands could be the self-assembling 6-diphenylphosphinopyridone/rhodium catalyst (6-DPPon see Scheme 1) de...

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Section: Scheme 1 Design Of a Domino Hydroformylation-aminocatalytic mentioning

confidence: 99%

Tandem Regioselective Rhodium-Catalyzed Hydroformylation–Enantioselective Aminocatalytic anti-Mannich Reaction

Diezel

Breit

2014

Synthesis

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“…The following substrates were purchased from commercial sources and distilled prior to use: 1-octene (Acros), vinylcyclohexene (Acros), 5-hexen-1-ol (VWR/Merck), allylbenzene (AlfaAesar), 3,3-dimethylbutene (AlfaAesar). The following substrates were prepared according to reported literature procedures: N-allylphthalimide, 17 hex-5-enyl acetate, 18 hex-5-enyloxymethylbenzene, 19 hex-5-enyl phenylcarbamate, 20 hex-5-en-1-yl benzoate, 21 N-methyl-N-phenylpent-4-enamide, 22 methylundec-10-enoate. 23…”

Section: Scheme 1 Classic Biginelli Reactionmentioning

confidence: 99%

Tandem Hydroformylation-Biginelli Reaction

Fuchs

Nasr‐Esfahani

Diab

et al. 2013

Synlett

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“…55−64 The majority of the syntheses use the chiral pool for at least one stereocenter, 55,57,58,[60][61][62]64 and a common strategy for tetrahydropyran (THP) formation has been oxa-Michael addition to an α,β-unsaturated carbonyl. 55,57,63 A straightforward extension of these considerations to (+)-decarestrictine L (3) from the enantiomer of the pyrenophorol starting material 14 is outlined in Scheme 9. We chose the precedented TBAF-mediated desilylation/oxa-Michael cascade of enone 16 for tetrahydropyran formation, suggesting an AHF/Wittig olefination of Z-enol acetate 17 followed by deacetylation to yield 16.…”

Section: ■ Introductionmentioning

confidence: 99%

Asymmetric Hydroformylation-Initiated Tandem Sequences for Syntheses of (+)-Patulolide C, (−)-Pyrenophorol, (+)-Decarestrictine L, and (+)-Prelog Djerassi Lactone

2014

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Four different Rh-catalyzed asymmetric hydroformylation (AHF) tandem reactions have been developed in the context of the total syntheses of (+)-patulolide C, (-)-pyrenophorol, (+)-decarestrictine L, and (+)-Prelog-Djerassi lactone. A total synthesis of (+)-patulolide C has been accomplished in three steps utilizing a Rh(I)-catalyzed Z-selective anti-Markovnikov hydroacetoxylation of a known alkyne to give a Z-enol acetate with excellent selectivity. An AHF/intramolecular Wittig olefination cascade was utilized to set the C4-hydroxyl stereochemistry, E-olefin geometry, and form the macrolactone. In addition, both (-)-pyrenophorol and (+)-decarestrictine L have been synthesized from the enantiomeric (4R)- and (4S)-4-(tert-butyldimethylsiloxy)-1-pentyne in five and four steps, respectively. These syntheses feature Ru(II)-catalyzed Z-selective anti-Markovnikov hydroacetoxylation of terminal alkynes followed by AHF/Wittig olefination sequences to rapidly establish functionality and stereogenicity. A synthesis of (+)-Prelog-Djerassi lactone was accomplished in three isolations from the known 1-vinyl-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane ortho ester. An AHF/crotylation tandem sequence has been developed to set the C2-C4 stereochemistry. An asymmetric hydrogenation was employed to set the C6 stereochemistry, resulting in an especially efficient enantioselective synthesis from achiral starting material. In summary, these syntheses have greatly improved efficiency in terms of atom-economy, catalytic stereoselective transformations, inexpensive reagents, step-counts, and overall yield when compared with previous synthetic attempts.

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A concise enantioselective synthesis of (+)-decarestrictine L via proline-catalyzed sequential α-aminooxylation and Horner–Wadsworth–Emmons olefination

Cited by 20 publications

References 27 publications

Tandem Regioselective Rhodium-Catalyzed Hydroformylation–Enantioselective Aminocatalytic anti-Mannich Reaction

Tandem Regioselective Rhodium-Catalyzed Hydroformylation–Enantioselective Aminocatalytic anti-Mannich Reaction

Tandem Hydroformylation-Biginelli Reaction

Asymmetric Hydroformylation-Initiated Tandem Sequences for Syntheses of (+)-Patulolide C, (−)-Pyrenophorol, (+)-Decarestrictine L, and (+)-Prelog Djerassi Lactone

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