Transition Metal Free C–N Bond Forming Dearomatizations and Aryl C–H Aminations by in Situ Release of a Hydroxylamine-Based Aminating Agent

Abstract

We outline a simple protocol that accesses directly unprotected secondary amines by intramolecular C–N bond forming dearomatization or aryl C–H amination. The method is dependent on the generation of a potent electrophilic aminating agent released by in situ deprotection of O-Ts activated N-Boc hydroxylamines.

Generation and application of Cu-bound alkyl nitrenes for the catalyst-controlled synthesis of cyclic β-amino acids

“…To obtain further insights, we employed 4-OH substituted substrate 15 , which would stabilize and trap a spiro intermediate by isomerization to the corresponding dienone if it were to form under these conditions. 31 The outcome was rather unexpected and distinct from that of the Rh catalysis ( Scheme 6b ). Both spirocycle 16 and 6-membered ring 17 were formed in excellent combined yields.…”

A Metal‐Free Direct Arene C−H Amination

“…double as large coupling to N. Additional support was gained by radical trapping experiments (Scheme 4 and Scheme S3): the reaction was almost totally inhibited when TEMPO or BHT were used as radical scavenger, suggesting that radical species are present in the reaction. The postulated aminyl radical, formed after the SET process via mesolysis, was efficiently trapped by BHT (product 120 , which also could have been formed by Bower's concerted mechanism [12a] ). This provides evidence for the formation of an aminyl radical during the reaction course.…”

Merging Brønsted Acid and Hydrogen‐Bonding Catalysis: Metal‐Free Dearomatization of Phenols via ipso‐Friedel‐Crafts Alkylation to Produce Functionalized Spirolactams

“…The use of thiourea 6 only did not promote the spirocyclization reaction at all and fumaric acid ( 9 ) or (thio)urea 7 , 8 were also ineffectual in this reaction (entries 9–12). Although the reaction in entries 6 and 7 indicated similar results, we decided to combine 6 and 4 as mild Brønsted acid was the best cooperative catalyst system for dearomative spirocyclization from the viewpoint of functional group tolerance, economy, and availability …”