A Carbohydrate-Based Approach for the Total Synthesis of (−)-Dinemasone B, (+)-4a-epi-Dinemasone B, (−)-7-epi-Dinemasone B, and (+)-4a,7-Di-epi-dinemasone B

Xue, Xiaochao; Yin, Zhaojun; Meng, Xiangbao; Li, Zhongjun

doi:10.1021/jo4015694

Cited by 14 publications

(18 citation statements)

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“…4 Soon after, we reported the stereoselective total synthesis of (À)-dinemasone B (1) and its isomers starting from D-glucose derivatives for the first time. 5 Herein, we present the concise synthesis of ent-4-deoxy-2,3-di-epi-dinemasone BC utilizing a chiral substrate for the direct and efficient construction of the core structure.…”

mentioning

confidence: 99%

Concise and direct construction of cis-pyrano[4,3-b]pyran-5-one skeleton from glucal derivatives: synthesis of ent-4-deoxy-2,3-di-epi-dinemasone BC

Xue

Yin

et al. 2015

Tetrahedron Letters

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confidence: 99%

Concise and direct construction of cis-pyrano[4,3-b]pyran-5-one skeleton from glucal derivatives: synthesis of ent-4-deoxy-2,3-di-epi-dinemasone BC

Xue

Yin

et al. 2015

Tetrahedron Letters

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“…Aldehyde 102 is produced from 101 using TEMPO/BAIB. [34] Scheme 2.23: Aldehyde formation in the dinemasone synthesis. [34] Following oxidation, olefination of aldehydes 95 and 96 must produce the E-alkene in order to obtain the appropriate geometry of (-)-TAN-2483B's E-propenyl sidechain as in compounds 97 and 98 (Scheme 2.24).…”

Section: Side-chain Installationmentioning

confidence: 99%

“…[34] Scheme 2.23: Aldehyde formation in the dinemasone synthesis. [34] Following oxidation, olefination of aldehydes 95 and 96 must produce the E-alkene in order to obtain the appropriate geometry of (-)-TAN-2483B's E-propenyl sidechain as in compounds 97 and 98 (Scheme 2.24). Both Julia-Kocienski and Takai-Utimoto methodologies have been reported to achieve similar transformations.…”

Section: Side-chain Installationmentioning

confidence: 99%

“…Both Julia-Kocienski and Takai-Utimoto methodologies have been reported to achieve similar transformations. [34] Scheme 2.24: Proposed olefination to install the propenyl side-chain.…”

Section: Side-chain Installationmentioning

confidence: 99%

“…The advantage of the Julia-Kocienski reaction is the enhanced selectivity attributable to the sterically demanding phenyl substituent on the tetrazole. This methodology has been used in a recent synthesis of the related dinemasone species (Section 1.3.3, Figure 1.5) published by Li and co-workers (Scheme 2.23) [34] , in which aldehyde 100 is reacted with the Julia-Kocienski reagent 103 to install the E-propenyl side chain of 104. Notably the lactone ring is stable under these conditions.…”

Section: Side-chain Installationmentioning

confidence: 99%

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Toward the Synthesis of the Fungal Metabolite (-)-TAN-2483B

Phipps¹

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In the search of chemical species with potential therapeutic biological activity, synthetic chemists have looked to nature for inspiration. Molecules built by biological machinery often have structures predisposed for biological interaction. (-)-TAN-2483B and the related compounds (-)-TAN-2483A, and waol A are fungal metabolites that display biological activity in kinase inhibition and parathyroid-induced bone resorption. Though total syntheses of (-)-TAN-2483A and waol A have been achieved, the established methodology does not afford access to (-)-TAN-2483B owing to the unique relative configuration about the ring system. Derivatives of D-galactal have been synthesised, and functionalised at the C-1 and C-2 positions, laying the groundwork for a route to (-)-TAN-2483B and analogues. Using D-galactal derivatives is advantageous as it circumvents some difficult transformations in the existing method for analogue synthesis. The functionalities installed were halide and formyl groups at the C-2 position, and acetylenes at the C-1 position. The synthesis of 2-haloglycals from tri-O-acetyl-D-galactal using N-halosuccinimides was achieved in 32% and <37% for the bromo- and iodo- variants respectively. Vilsmeier-Haack formylation was explored using per-benzylated and per-acetylated galactals as substrates. Formylation of the per-benzylated species was achieved in 78% yield in accordance with literature values. Vilsmeier-Haack formylation on the per-acetylated galactal has not been reported and the glycal was found to be a poor substrate for the formylation. Theories regarding the incompatibility of the per-acetylated species with Vilsmeier-Haack conditions were developed. Ferrier-type alkynylation of the 2-halo/formylglycals was explored, with yields up to 17% and 13% for the bromo- and iodo- species (unoptimised), and 7% for 2-formylglycal (after optimisation studies). The resulting 1-ethynyl-2-formyl/halo-2,3-unsaturated pyrans could be potential intermediates en route to the furanone ring of the target compound.

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The J ulia– K ocienski Olefination

Blakemore¹,

Sephton

Ciganek

2018

Organic Reactions

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The Julia–Kocienski olefination is a direct connective synthesis of alkenes via the addition of metalated aryl alkyl sulfones to carbonyl compounds. The activating aromatic group associated with the sulfone must possess electrophilic character, and alkene formation occurs via β‐alkoxy sulfone formation, transfer of the aryl group from sulfur to oxygen via a Smiles rearrangement, and then elimination of sulfur dioxide and an aryloxide anion from the resulting β‐aryloxy sulfinate anion. The olefination process itself and the methods used to prepare the requisite sulfone substrates are tolerant of a wide variety of functional groups, and a variety of alkene targets can be prepared. Stereoselectivity is dependent on the nature of the sulfone, the carbonyl compound, the activating aryl moiety, and the reaction conditions. This chapter describes theoretical and operational aspects of the Julia–Kocienski olefination such that the reader will be able to obtain optimal results in his/her own research. A detailed mechanistic overview is included to account for the factors that influence stereoselectivity and yield. Methods for introducing sulfone activators into fragments of interest, best practices for generating sulfone anions, and optimal strategies for targeting different classes of alkene targets are discussed. Functional group compatibilities, reaction variants, and a comparison to other methods of alkene synthesis are also presented. Tabular surveys are organized according to type of alkene synthesized, with an emphasis on the degree of substitution and the level of conjugation about the newly formed double bond. The literature is covered from the initial disclosure of the Julia–Kocienski olefination in 1991 to the first quarter of 2016.

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A Carbohydrate-Based Approach for the Total Synthesis of (−)-Dinemasone B, (+)-4a-epi-Dinemasone B, (−)-7-epi-Dinemasone B, and (+)-4a,7-Di-epi-dinemasone B

Cited by 14 publications

References 47 publications

Concise and direct construction of cis-pyrano[4,3-b]pyran-5-one skeleton from glucal derivatives: synthesis of ent-4-deoxy-2,3-di-epi-dinemasone BC

Concise and direct construction of cis-pyrano[4,3-b]pyran-5-one skeleton from glucal derivatives: synthesis of ent-4-deoxy-2,3-di-epi-dinemasone BC

Toward the Synthesis of the Fungal Metabolite (-)-TAN-2483B

The J ulia– K ocienski Olefination

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