Enantioselective Synthesis of 4<i>H</i>‐Pyrans Through Organocatalytic Asymmetric Formal [3+3] Cycloadditions of 2‐(1‐Alkynyl)‐2‐alken‐1‐ones with β‐Keto Esters

Yue, Zhenting; Li, Wenbo; Liu, Lu; Wang, Cuihong; Zhang, Junliang

doi:10.1002/adsc.201600591

Cited by 26 publications

(15 citation statements)

References 72 publications

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“…Based on the above results and on related references,, a plausible catalytic mechanism for the [3+3] annulation is depicted in Figure . The chiral organocatalyst VI acts as a bifunctional catalyst simultaneously interacting with both electrophile 1a and nucleophile 2a through hydrogen bonding to form a highly ordered transition state (TS).…”

Section: Resultssupporting

confidence: 54%

“…The substrates 2‐(1‐alkynyl)‐2‐alken‐1‐ones were prepared according to reported procedures. Compounds 1a – j and 1q – s were prepared by known methods , , . Compounds 1k – p were also prepared by using reported procedures…”

Section: Methodsmentioning

confidence: 99%

“…We envisioned that 2‐(1‐alkynyl)‐2‐alken‐1‐one might be the kind of enyne that would react with barbiturate to afford pyrano[2,3‐ d ]pyrimidines. Such 2‐(1‐alkynyl)‐2‐alken‐1‐ones are important compounds as useful building blocks in organic chemistry …”

Section: Introductionmentioning

confidence: 99%

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An Organocatalytic Synthesis of Chiral Pyrano[2,3‐d]pyrimidines through [3+3] Annulation of 1,3‐Dimethyl‐barbituric Acid with 2‐(1‐Alkynyl)‐2‐alken‐1‐ones

et al. 2018

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An efficient enantioselective [3+3] annulation has been developed to synthesize chiral pyrano[2,3‐d]pyrimidines from 1,3‐dimethyl‐barbituric acid and 2‐(1‐alkynyl)‐2‐alken‐1‐ones. A thiourea‐tertiary amine bifunctional catalyst was synthesized and applied in the construction of the framework of chiral pyrano[2,3‐d]pyrimidines. The reaction proceeds smoothly on a broad range of substrates (18 examples) to produce the target products in moderate to good yields and enantioselectivities. Reduced temperature leads to an improvement of enantiomeric excesses. Steric hindrance plays an important role in the performance of the reaction.

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Section: Resultssupporting

confidence: 54%

Section: Methodsmentioning

confidence: 99%

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An Organocatalytic Synthesis of Chiral Pyrano[2,3‐d]pyrimidines through [3+3] Annulation of 1,3‐Dimethyl‐barbituric Acid with 2‐(1‐Alkynyl)‐2‐alken‐1‐ones

et al. 2018

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“…Accordingly, a three‐step procedure was adopted in order to obtain these derivatives in higher yields. This protocol included the protection of one amino group as phthalimide, followed by acylation with the corresponding phosphoric chloride, and deprotection using N 2 H 4 hydrate . Although this procedure included two flash chromatographic purifications, ent ‐ 3 and 4 were isolated in over 50% overall yields.…”

Section: Resultsmentioning

confidence: 99%

1,2‐Diamine‐Derived (thio)Phosphoramide Organocatalysts in Asymmetric Michael Additions

2020

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Phosphoramides and thiophosphoramides were prepared from optically pure C2‐symmetric 1,2‐diamines and were used as chiral organocatalysts in the asymmetric Michael additions of aldehydes and ketones to N‐substituted maleimides. The 1,2‐diphenylethane‐1,2‐diamine derived thiophosphoramide, which could be prepared in good yield in a one‐step procedure, was found to be more active and selective catalyst in the addition of aldehydes to various maleimide derivatives, when compared to sulfonamides having the same backbone. Products resulted in reactions of ketones with maleimides were also obtained in high yields and enantioselectivities. The thiophosphoramide derivative was also efficient in the asymmetric conjugate addition of carbonyl compounds to β‐nitrostyrene and in the reaction of nitromethane with α,β‐unsaturated ketones. Based on results obtained with (thio)phosphoramides in asymmetric additions to maleimides it was suggested that a weaker, more flexible hydrogen‐bonding of the rigid electrophile to the catalyst is responsible for the improved performance of these bifunctional organocatalysts, as compared with sulfonamides.

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“…In 2016, the Zhang group developed the enantioselective [3+3] annulation for the synthesis of chiral 4H-pyrans between 2-(1alkynyl)-2-alken-1-ones 34 and -keto esters 35 catalyzed by cyclohexyldiamine-based thiourea-tertiary amine 36. 15 Keto esters 35 participate as dinucleophiles in the annulation process. Under mild conditions, a wide range of 4Hpyrans derivatives 37 were obtained in moderate yields with good enantioselectivities.…”

Section: Synthesis Of Oxygen Heterocyclesmentioning

confidence: 99%

Organocatalyzed [3+3] Annulations for the Construction of Heterocycles

Zhu¹,

Huang

2020

Synthesis

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Six-membered heterocyclic systems are widely distributed in many natural products and pharmaceuticals, and the construction of highly functionalized six-membered heterocyclic compounds is an important topic in modern organic synthesis. Organocatalyzed [3+3] annulations represents an important method for assembling a substantial variety of six-membered cycles that contain one or more heteroatoms. This review describes the development of organocatalyzed [3+3] annulations for the synthesis of six-membered heterocycles, including organocatalysis using secondary amines, tertiary amines, phosphines, chiral phosphoric acids and N-heterocyclic carbenes.1 Introduction2 Secondary Amine Catalyzed [3+3] Annulations2.1 Synthesis of Nitrogen Heterocycles2.2 Synthesis of Oxygen Heterocycles2.3 Synthesis of Sulfur Heterocycles3 Tertiary Amine Catalyzed [3+3] Annulations3.1 Catalysis through Multiple Hydrogen-Bonding Interactions3.2 Catalysis of Tertiary Amines as Lewis Bases4 Phosphine-Catalyzed [3+3] Annulations4.1 Synthesis of Nitrogen Heterocycles4.2 Synthesis of Oxygen Heterocycles4.3 Synthesis of Heterocycles Containing Two or More Heteroatoms5 Chiral Phosphoric Acid Catalyzed [3+3] Annulations5.1 Synthesis of Nitrogen Heterocycles5.2 Synthesis of Heterocycles Containing Two or More Heteroatoms6 N-Heterocyclic Carbene Catalyzed [3+3] Annulations6.1 Synthesis of Nitrogen Heterocycles6.2 Synthesis of Oxygen Heterocycles6.3 Synthesis of Heterocycles Containing Two or More Heteroatoms7 Conclusion and Outlook

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Enantioselective Synthesis of 4H‐Pyrans Through Organocatalytic Asymmetric Formal [3+3] Cycloadditions of 2‐(1‐Alkynyl)‐2‐alken‐1‐ones with β‐Keto Esters

Abstract: Scheme 2. Va rious b-keto ester compounds.R eactions were carried out with 0.2 mmol of 1,0 .6 mmolo f2 and 20 mol% catalyst at room temperature.Isolated yields.Scheme 3. X-ray crystals tructure of (R)-3ag.Scheme 4. Control experiments.

Cited by 26 publications

References 72 publications

An Organocatalytic Synthesis of Chiral Pyrano[2,3‐d]pyrimidines through [3+3] Annulation of 1,3‐Dimethyl‐barbituric Acid with 2‐(1‐Alkynyl)‐2‐alken‐1‐ones

An Organocatalytic Synthesis of Chiral Pyrano[2,3‐d]pyrimidines through [3+3] Annulation of 1,3‐Dimethyl‐barbituric Acid with 2‐(1‐Alkynyl)‐2‐alken‐1‐ones

1,2‐Diamine‐Derived (thio)Phosphoramide Organocatalysts in Asymmetric Michael Additions

Organocatalyzed [3+3] Annulations for the Construction of Heterocycles

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