5-Bromomethyl-4,5-dihydroisoxazoles

Mosher, Michael; Norman, Amber L.; Shurrush, Khriesto A.

doi:10.1016/j.tetlet.2009.07.106

Cited by 26 publications

(6 citation statements)

References 18 publications

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“…[3c] We disclose here a catalytic method for the highly enantioselective iodoetherification of b,g-unsaturated oximes, a hitherto unprecedented asymmetric transformation (Scheme 1). [9] Isoxazolines are an important class of com-pounds found in several biologically active agents and versatile intermediates in organic synthesis. [10] In spite of their utility in chemistry and biology, there is no report on the enantioselective synthesis of isoxazolines containing a quaternary stereogenic center.…”

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confidence: 99%

Catalytic Enantioselective Iodoetherification of Oximes

2013

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Organocatalysis: The first catalytic enantioselective iodoetherification of oximes is developed using commercially available N‐iodosuccinimide. In the presence of a dihydrocinchonidine‐derived thiourea (10 mol %), β,γ‐unsaturated oximes undergo facile iodoetherification to produce Δ2‐isoxazolines containing a quaternary stereogenic center generally in high yield with good to excellent enantioselectivity.

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confidence: 99%

Catalytic Enantioselective Iodoetherification of Oximes

2013

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“…In contrast, aldehyde-or ketone-derived nucleophiles had never been subjected to halocyclization reactions. 26 With the objective of bridging this gap, our group recently reported the iodocyclization of ketone derivative, specifically the β,γ-unsaturated oximes 28 (Scheme 10). 27 The reasons behind the choice of an oxime as the nucleophile were twofold.…”

Section: Methodsmentioning

confidence: 99%

Catalytic Enantioselective Halocyclizations beyond Lactones: Emerging Routes to Enantioenriched Nitrogenous Heterocycles

Tripathi

Mukherjee

2013

Synlett

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Electrophilic halogen-induced reactions of unactivated olefins are an important class of transformations, whose catalytic enantioselective variants have surfaced during the past few years as effective means of olefin heterodifunctionalization. This article covers important developments in the area of enantioselective halocyclizations, specifically in the context of the synthesis of nitrogenous heterocycles.Stereoselective functionalization of unactivated olefins is possibly the most sought-after strategy for generating diversity from easily accessible starting materials. In this regard, the catalytic asymmetric homofunctionalization of unactivated olefins might be considered as a successful and rather mature area of research, thanks to the discovery of methods for epoxidation, dihydroxylation, aziridination, and, to some extent, diamination. Heterodifunctionalization, on the other hand, remained a relatively less well explored territory. Electrophilic halogen-induced activation of olefins followed by nucleophilic addition is a remarkably general strategy for stereoselective olefin heterodifunctionalization (Scheme 1). 1 Halolactonization [Scheme 1 (B); Nu = CO 2 H] is the most prominent example in this category. Even though halolactonization was discovered more than a century ago 2 and has been applied to the synthesis of numerous natural and nonnatural targets, 3 the development of catalytic enantioselective halolactonization and related halocyclization reactions has proved notoriously difficult. Because proven approaches to asymmetric catalysis failed when applied to halocyclization reactions, the field of asymmetric halocyclization was, until recently, virtually unexplored, except for some sporadic examples involving chiral phase-transfer catalysts and chiral Lewis acids. 4 The past few years have witnessed a renaissance in the area of enantioselective olefin halofunctionalization. 5,6 As expected, halolactonization was the first such reaction to catch the attention of researchers, and a number of methods for highly enantioselective chloro-, bromo-, and iodolactonization reactions were developed with the help of a range of structurally dissimilar catalysts. 7 These reactions were not restricted to olefins, as conjugated enynes 8 and alkynes 9 were also subjected to enantioselective halolactonizations. From these reports, the mechanistic pictures associated with these reactions became clearer and a foundation was laid for further developments. Subsequently, several other halocyclization reactions joined the Chandra Bhushan Tripathi (left) received his B.Sc.Scheme 1 Electrophilic halogen-induced stereoselective olefin functionalization (A) and its intramolecular variant, halocyclization (B) SYNLETT 2014, 25, 0163-0169 Advanced online publication: 03.12.20130 9 3 6 -5 2 1 4 1 4 3 7 -2 0 9 6

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“…Among precedent synthetic methods, the functionalization of unactivated olefins provides a rapid construction of different heterocycles [16–17]. More specifically, the formation of isoxazoline and pyrazoline cores via alkene heterofunctionalization of allyl ketone oximes and/or allyl ketone tosylhydrazones has been well documented [18–22]. For example, diverse halonium sources have been utilized for the synthesis of isoxazolines via halocyclization.…”

Section: Introductionmentioning

confidence: 99%

Hypervalent iodine-mediated Ritter-type amidation of terminal alkenes: The synthesis of isoxazoline and pyrazoline cores

Park¹,

Kim²,

Song³

et al. 2018

Beilstein J. Org. Chem.

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Hypervalent iodine-mediated olefin functionalization provides a rapid gateway towards accessing both various heterocyclic cores and functional groups. In this regard, we have developed a Ritter-type alkene functionalization utilizing a PhI(OAc)2 ((diacetoxyiodo)benzene, PIDA)/Lewis acid combination in order to access isoxazoline and pyrazoline cores. Based on allyl ketone oximes and allyl ketone tosylhydrazones, we have developed an alkene oxyamidation and amido-amidation protocol en route to accessing both isoxazoline and pyrazoline cores. Additionally, acetonitrile serves as both the solvent and an amine source in the presence of this PIDA/Lewis acid combination. This operationally straightforward and metal-free protocol provides an easy access to isoxazoline and pyrazoline derivatives.

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5-Bromomethyl-4,5-dihydroisoxazoles

Cited by 26 publications

References 18 publications

Catalytic Enantioselective Iodoetherification of Oximes

Catalytic Enantioselective Iodoetherification of Oximes

Catalytic Enantioselective Halocyclizations beyond Lactones: Emerging Routes to Enantioenriched Nitrogenous Heterocycles

Hypervalent iodine-mediated Ritter-type amidation of terminal alkenes: The synthesis of isoxazoline and pyrazoline cores

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