Ascending of Cycloaddition Strategy for N–O Heterocycles

Ghosh, Prasanjit; Mondal, Swati Lekha; Baidya, Mahiuddin

doi:10.1055/a-1703-6448

Cited by 3 publications

(1 citation statement)

References 76 publications

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“…1,2-Oxazine derivatives represent an important class of nitrogen–oxygen heterocycles which are widely used in organic chemistry [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Reductive cleavage of the N–O bond makes 1,2-oxazine derivatives useful precursors to aminoalcohols and functionalized carbonyl compounds.…”

Section: Introductionmentioning

confidence: 99%

[3+3]-Annulation of Cyclic Nitronates with Vinyl Diazoacetates: Diastereoselective Synthesis of Partially Saturated [1,2]Oxazino[2,3-b][1,2]oxazines and Their Base-Promoted Ring Contraction to Pyrrolo[1,2-b][1,2]oxazine Derivatives

et al. 2023

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A rhodium(II)-catalyzed reaction of cyclic nitronates (5,6-dihydro-4H-1,2-oxazine N-oxides) with vinyl diazoacetates proceeds as a [3+3]-annulation producing bicyclic unsaturated nitroso acetals (4a,5,6,7-tetrahydro-2H-[1,2]oxazino[2,3-b][1,2]oxazines). Optimization of reaction conditions revealed the use of Rh(II) octanoate as the preferred catalyst in THF at room temperature, which allows the preparation of target products in good yields and excellent diastereoselectivity. Under basic conditions, namely, the combined action of DBU and alcohol, these nitroso acetals undergo ring contraction of an unsaturated oxazine ring into the corresponding pyrrole. Both transformations can be performed in a one-pot fashion, thus constituting a quick approach to oxazine-annulated pyrroles from available starting materials, such as nitroalkenes, olefins, and diazo compounds.

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Section: Introductionmentioning

confidence: 99%

[3+3]-Annulation of Cyclic Nitronates with Vinyl Diazoacetates: Diastereoselective Synthesis of Partially Saturated [1,2]Oxazino[2,3-b][1,2]oxazines and Their Base-Promoted Ring Contraction to Pyrrolo[1,2-b][1,2]oxazine Derivatives

et al. 2023

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A computational study of 1,3-dipolar cycloadditions of nitrile oxides with dienes

Kiss

Escorihuela

2023

Tetrahedron

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Chiral Brønsted Acid-Catalyzed Regio-, Diastereo-, and Enantioselective Formal [2 + 2 + 2] Cycloaddition of 3-Vinyl-1H-indoles with Nitrosobenzenes

Yu,

Diaz,

Kroeger

et al. 2024

ACS Catal.

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A chiral Brønsted acid-catalyzed synthetic method that enables the enantioselective formal [2 + 2 + 2] cycloaddition of 3-vinyl-1H-indoles with nitrosobenzenes is described. Through this previously unknown mode of reactivity of the nitrosoarene, the ring formation protocol offers access to a wide variety of fully substituted 1,2-oxazinanes as a single regioisomer. With four stereogenic centers generated in the product, the N,O-heterocycle was also furnished, in most cases, as a single diastereomer in yields of up to 94% and with enantiomeric excess (ee) values of up to 99%. The synthetic utility of the catalytic method was demonstrated by the 2 mmol scale preparation of one example and its further functional group transformations. Included in this is the selective conversion of the 1,2-oxazinane to either its tetrahydrofuran or a partially hydrogenated pyrrole derivative. Experimental and computational studies based on azaphilic and hydrogen-bonding interactions between the two substrates with the chiral phosphoric acid provide insight into the observed product selectivities.

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Ascending of Cycloaddition Strategy for N–O Heterocycles

Cited by 3 publications

References 76 publications

[3+3]-Annulation of Cyclic Nitronates with Vinyl Diazoacetates: Diastereoselective Synthesis of Partially Saturated [1,2]Oxazino[2,3-b][1,2]oxazines and Their Base-Promoted Ring Contraction to Pyrrolo[1,2-b][1,2]oxazine Derivatives

[3+3]-Annulation of Cyclic Nitronates with Vinyl Diazoacetates: Diastereoselective Synthesis of Partially Saturated [1,2]Oxazino[2,3-b][1,2]oxazines and Their Base-Promoted Ring Contraction to Pyrrolo[1,2-b][1,2]oxazine Derivatives

A computational study of 1,3-dipolar cycloadditions of nitrile oxides with dienes

Chiral Brønsted Acid-Catalyzed Regio-, Diastereo-, and Enantioselective Formal [2 + 2 + 2] Cycloaddition of 3-Vinyl-1H-indoles with Nitrosobenzenes

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