Brookhart's Acid‐Catalyzed Switchable RegioselectiveN‐Alkylation of Arylamines/Heterocyclic Amines with Cyclopropylcarbinols by Temperature Regulation

Abstract

Dedicated to Professor Martin Oestreich on the occasion of his 50 th birthday.

Halogen Promoted Desulfurative Cleavage of Cyclopropylmethyl Thioethers and Amination of the Formed Cyclopropylcarbinyl Cations

“…Unfortunately, heterocyclic substituents at the propargylic position (1 ka) were not tolerated, delivering complex reaction mixtures (entry 11). Finally, we evaluated the influence of the substituent on the thioorganyl moiety, which is cleaved (entries [12][13][14][15][16], observing that unfunctionalized alkyl chains showed similar behavior to the model compound 1 aa (entry 12). By contrast, aromatic sulfides 1 ac-ad afforded slightly lower yields (entries 13 and 14), although the presence of electron-donating groups attached to the arene (1 ac) achieved better results than 1 ad.…”

“…More recently, Chazra reported an elegant protocol for the homoallylation of anilines by activating cyclopropylcarbinols with Brookhart acid as the catalyst (Scheme 1c). [16] Also, in 2022, Wang described cyclopropane ring-opening reactions to synthesize E-homoallyl triflimides using Ca(NTf 2 ) 2 in hexafluoroisopropanol (HFIP) (Scheme 1d). [17] Although most common sources for cyclopropylcarbinyl cations are based on the activation of alcohols or ethers, [10] other functional groups that remain underexplored could also be employed.…”

“…Less basic nucleophiles like azides [14] or TMSCN [15] were successfully employed in stereoselective ring‐opening of highly substituted cyclopropyl ethers promoted by iron (Scheme 1b) and tin salts. More recently, Chazra reported an elegant protocol for the homoallylation of anilines by activating cyclopropylcarbinols with Brookhart acid as the catalyst (Scheme 1c) [16] . Also, in 2022, Wang described cyclopropane ring‐opening reactions to synthesize E ‐homoallyl triflimides using Ca(NTf 2 ) 2 in hexafluoroisopropanol (HFIP) (Scheme 1d) [17] .…”

Direct access to hydrazides and amides from carboxylic acids via acyloxyphosphonium ion

“…Many synthetic approaches to synthesize C–N-containing compounds have been published in the literature over the last few decades. 6 The most common method for producing hydrazides is the reaction of hydrazines with anhydrides or acyl halides.…”