Stereoselective cycloaddition of 1-glucosyl-1,3-butadienes with tert-butyl 2H-azirine-3-carboxylate, glyoxylates and imines

Alves, M. I. Caetano; Almeida, Isabel; Fortes, A. Gil; Freitas, A. P.

doi:10.1016/s0040-4039(03)01696-4

Cited by 6 publications

(1 citation statement)

References 14 publications

(9 reference statements)

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“…After examining a variety of reaction conditions (i.e., solvents, Lewis acids, and temperatures), we identified optimal reaction conditions, which involved heating 8 and 9 in hexafluoroisopropanol (HFIP) at 50 °C for 16 h. This gave rise to cycloadducts 7a (desired) and its C15 epimer, 7b , as the major productsin a 1:1 ratio (55% combined yield) . Sugars have rarely been employed to dictate stereochemistry in intermolecular inverse electron-demand hetero-Diels–Alder reactions, where the sugar resides on the dienophilic component. − Furthermore, in the present example, the sugar is not used as a chiral auxiliary, but it is a component of both (−)-secologanin ( 6 ) and (−)-strictosidine ( 4 ). Thus, our approach involving early introduction of the sugar to guide stereochemical outcomes represents a useful strategy for accessing single enantiomers of glycosylated natural products.…”

Section: Resultsmentioning

confidence: 98%

Total Synthesis of (−)-Strictosidine and Interception of Aryne Natural Product Derivatives “Strictosidyne” and “Strictosamidyne”

et al. 2021

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Monoterpene indole alkaloids are a large class of natural products derived from a single biosynthetic precursor, strictosidine. We describe a synthetic approach to strictosidine that relies on a key facially selective Diels–Alder reaction between a glucosyl-modified alkene and an enal to set the C15–C20–C21 stereotriad. DFT calculations were used to examine the origin of stereoselectivity in this key step, wherein two of 16 possible isomers are predominantly formed. These calculations suggest the presence of a glucosyl unit, also inherent in the strictosidine structure, guides diastereoselectivity, with the reactive conformation of the vinyl glycoside dienophile being controlled by an exo-anomeric effect. (−)-Strictosidine was subsequently accessed using late-stage synthetic manipulations and an enzymatic Pictet–Spengler reaction. Several new natural product analogs were also accessed, including precursors to two unusual aryne natural product derivatives termed “strictosidyne” and “strictosamidyne”. These studies provide a strategy for accessing glycosylic natural products and a new platform to access monoterpene indole alkaloids and their derivatives.

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Section: Resultsmentioning

confidence: 98%

Total Synthesis of (−)-Strictosidine and Interception of Aryne Natural Product Derivatives “Strictosidyne” and “Strictosamidyne”

et al. 2021

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Diels‐Alder Reactions of Imino Dienophiles

et al. 2005

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In comparison to all carbon [4 + 2] cycloadditions, Diesl‐Alder reactions are still in their infancy. The last four decades, however, have seen intensive research in this area. The results if that synthetic organic chemists now have a powerful tool at their disposal for rapid construction of highly functionalized six‐membered nitrogen heterocycles, often in a regio‐, diastereo‐, and enantioselective manner. This chapter encompasses the topic of imine[4 + 2] cycloaddition reactions, of which there are a number of variants. This chapter is limited exclusively to imine and iminium ion dienophiles that undergo inter‐ and intramolecular Diels‐Alder reactions with acylic and cyclic all‐carbon 1,3‐dienes affording 1,2,5,6‐tetrahydropyridines as the initial cycloadducts. In situations where there is a mechanistic ambiguity, such as reactions that proceed via Mannich reactions, these mechanisms are included since it is difficult to know where to draw the line on coverage. A comprehensive discussion of each structural type of imino dienophiles covers the literature up to the middle of 2004. A general overview of mechanistic, regiochemical, and sterochemical considerations is also presented. Specific relevant exo/endo issues, remote diasteroselectivity and the use of chiral auxiliaries are discussed under each separate imine type. Separate sections have also been included that describe intramolecular reactions, as well as more recent advances in enantioselective cycloadditions involving chiral catalysts.

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Small Rings by Azide Chemistry

Gilchrist¹,

Alves

2009

Organic Azides

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Stereoselective cycloaddition of 1-glucosyl-1,3-butadienes with tert-butyl 2H-azirine-3-carboxylate, glyoxylates and imines

Abstract: Stereoselective Cycloaddition of 1-glucosyl-1,3butadienes with tert-Butyl-2H-azirine-3carboxylate, Glyoxylates and Imines

Cited by 6 publications

References 14 publications

Total Synthesis of (−)-Strictosidine and Interception of Aryne Natural Product Derivatives “Strictosidyne” and “Strictosamidyne”

Total Synthesis of (−)-Strictosidine and Interception of Aryne Natural Product Derivatives “Strictosidyne” and “Strictosamidyne”

Diels‐Alder Reactions of Imino Dienophiles

Small Rings by Azide Chemistry

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