Intermolecular Electrophilic Bromoesterification and Bromoetherification of Unactivated Cyclopropanes

Abstract

Abstract1,3‐difunctionalization of cyclopropane is an useful organic transformation. The corresponding 1,3‐difunctionalized products are synthetic synthons and building blocks in many organic syntheses. Many existing ring‐opening difunctionalization methodologies rely primarily on the use of donor−acceptor cyclopropanes, while the difunctionalization of unactivated cyclopropanes is less exploited. In this research, 1,3‐bromoesterification and 1,3‐bromoetherification of unactivated cyclopropanes were successfully achieved using N‐bromosuccinimide as the brominating agent with high yields and regioselectivity.magnified image

A copper-catalyzed four-component reaction of arylcyclopropanes, nitriles, carboxylic acids and N-fluorobenzenesulfonimide: facile synthesis of imide derivatives

“…So far, some impressive approaches for the three-component reaction of cyclopropane, especially ring-opening 1,3-difunctionalization have been investigated intensively. Various three-component reactions of cyclopropane with either one nucleophile and one electrophile, 3 or one nucleophile and one radical trapping agent or one radical species, 4 or even with two nucleophiles, 5 have been well established in the past few years. In sharp contrast, the corresponding four-component reactions which have many more difficulties in delicately controlling the subtle balance between reactivity and selectivity of each component, are still very scarce.…”

A Journey from June 2018 to October 2021 with N,N-Dimethylformamide and N,N-Dimethylacetamide as Reactants

“…1,3-Bromoesters have been isolated from the reaction of aryl cyclopropanes with NBS, DMF, and H 2 O (Scheme 30(a 1 )), which involves bromination of the three-membered ring leading to carbocation ArR 1 C ⊕ CH 2 CH 2 Br [86]. The subsequent attack of the oxygen of DMF via S N 1 or S N 2 mechanism affords ArR 1 C(OCH=N ⊕ Me 2 )(CH 2 CH 2 Br) which undergoes hydrolysis delivering the bromoester.…”

Solvent and catalyst-free bromofunctionalization of olefins using a mechanochemical approach

“…4 Thus, milder and more user-friendly halogen sources such as N-bromosuccinimide (NBS) and 1,3-dibromo-5,5dimethylhydantoin (DBDMH) are frequently employed in many bromofunctionalization reactions. 5 Well reported examples include bromocyclization reactions such as bromolactonization [6][7][8][9][10][11][12][13][14][15] and bromoetherication [16][17][18][19] as well as the more challenging intermolecular bromoesterication. [20][21][22][23][24][25][26] Because of the high polarity of the N-bromoimide reagents, polar solvents such as N,N-dimethylformamide and acetonitrile are oen required for good solvation which poses difficulties in the purication process.…”