Synthesis of Alkynes from Vinyl Triflates Using Tetrabutylammonium Fluoride

Okutani, Masaru; Mori, Yoshihiro

doi:10.1248/cpb.c15-00146

Cited by 8 publications

(3 citation statements)

References 36 publications

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“…Freshly prepared iodide 57 was subjected to a Nozaki-Hiyama reaction with acetaldehyde 58 to give alcohol 59 in 74% yield as a single diastereomer. A three-step transformation from alcohol 59, namely facial selective reduction of the exo-olefin ( product not shown, 93% yield), secondary alcohol oxidation ( product not shown, 89% yield), and triflation/TBAF-mediated elimination 57 and desilylation, gave alkyne 60 in 71% yield. Treatment of 60 with AlI 3 facilitated a Prins cyclization and provided the cyclization product 61 in 68% yield.…”

Section: (+)-Psiguadial B (Reisman 2016) 39mentioning

confidence: 99%

Construction of all-carbon quaternary stereocenters by catalytic asymmetric conjugate addition to cyclic enones in natural product synthesis

Wang

2020

Org. Chem. Front.

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Section: (+)-Psiguadial B (Reisman 2016) 39mentioning

confidence: 99%

Construction of all-carbon quaternary stereocenters by catalytic asymmetric conjugate addition to cyclic enones in natural product synthesis

Wang

2020

Org. Chem. Front.

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“…To perform the subsequent elimination reaction, 15 was treated with excess tetrabutylammonium fluoride (TBAF) at room temperature in N , N -dimethylformamide (DMF), using conditions originally reported by Mori (Scheme ). This afforded a mixture of the desired terminal alkyne 16 and a small amount of the isomeric allene 17 , which were separable by column chromatography. At this stage, we decided to epoxidize the C1–C10 alkene in intermediate 16 .…”

Section: Resultsmentioning

confidence: 99%

Synthesis of (+)-Lineariifolianone and Related Cyclopropenone-Containing Sesquiterpenoids

et al. 2019

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A synthesis of the proposed structure of lineariifolianone has been achieved in eight steps and 9% overall yield starting from (+)-valencene, leading to a reassignment of the absolute configuration of this unusual cyclopropenone-containing natural product. Key steps in the synthetic route include kinetic protonation of an enolate to epimerize the C7 stereocenter and a stereoconvergent epoxide opening to establish the trans-diaxial diol functionality. The syntheses of the enantiomers of two other closely related natural products are also reported, confirming that all three compounds belong to the eremophilane class of sesquiterpenoids.

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“…The eneimide 57 successfully underwent ring opening upon addition of the alkyllithium derived from ( R )- 30 to provide the diketone 75 in 48% yield after hydrolysis of the acylimine intermediate (Scheme ). The methyl ketone 75 was converted to the alkyne 77 by conversion to the vinyl triflate 76 , followed by elimination with TBAF (69%, two steps), or more conveniently in one step by vinyl triflate formation in the presence of excess base (81%). Removal of the p -methoxybenzyl ether with DDQ afforded a primary alcohol (not shown) that was oxidized to the aldehyde 78 (95%, two steps).…”

Section: Resultsmentioning

confidence: 99%

Development of a Modular Synthetic Route to (+)-Pleuromutilin, (+)-12-epi-Mutilins, and Related Structures

2017

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We describe the development of an enantioselective synthetic route to (+)-pleuromutilin (1), (+)-12-epi-mutilin, and related derivatives. A key hydrindanone was prepared in three steps and 48% overall yield from cyclohex-2-en-1-one. 1,4-Hydrocyanation provided a nitrile (53%, or 85% based on recovered starting material) that was converted to the eneimide 57 in 80% yield by the 1,2-addition of methyllithium to the nitrile function, cyclization, and in situ acylation with di-tert-butyldicarbonate. The eneimide 57 was employed in a 2-fold neopentylic coupling reaction with an organolithium reagent derived from the alkyl iodides (R)- or (S)-30, which contain the C11-C13 atoms of the target, to provide diastereomeric diketones in 60% or 48% yield (for coupling with (R)- or (S)-30, respectively). The diketone derived from (S)-30 contains the (S)-C12 stereochemistry found in pleuromutilin and was elaborated to an alkynylaldehyde. Nickel-catalyzed reductive cyclization of this alkynylaldehyde, to construct the eight-membered ring of the target, unexpectedly provided a cyclopentene (67%), which arises from participation of the C12-α-olefin in the transformation. The diketone derived from the enantiomeric C12-fragment (R)-30 underwent reductive cyclization to provide the desired product in 60% yield. This was elaborated to 12-epi-mutilin by a four-step sequence (39% overall). Installation of the glycolic acid residue followed by C12 epimerization (Berner et al. Monatsh. Chem. 1986, 117, 1073) generated (+)-pleuromutilin (1). (+)-12-epi-Pleuromutilin and (+)-11,12-di-epi-pleuromutilin were prepared by related sequences. This work establishes a convergent entry to the pleuromutilins and provides a foundation for the production of novel antibiotics to treat drug-resistant and Gram-negative infections.

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Synthesis of Alkynes from Vinyl Triflates Using Tetrabutylammonium Fluoride

Cited by 8 publications

References 36 publications

Construction of all-carbon quaternary stereocenters by catalytic asymmetric conjugate addition to cyclic enones in natural product synthesis

Construction of all-carbon quaternary stereocenters by catalytic asymmetric conjugate addition to cyclic enones in natural product synthesis

Synthesis of (+)-Lineariifolianone and Related Cyclopropenone-Containing Sesquiterpenoids

Development of a Modular Synthetic Route to (+)-Pleuromutilin, (+)-12-epi-Mutilins, and Related Structures

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