High Pressure Elicits Unexpected Transformations of Plain Nitroaromatics with 4‐(Cyclohex‐1‐en‐1‐yl)morpholine

Abstract

An unexpected reaction sequence occurs when simple nitroarenes and the readily available enamine 4‐(cyclohex‐1‐en‐1‐yl)morpholine are placed under high pressure. This one‐pot transformation leads to the generation of highly substituted compounds and presents different advantages such as (1) a rapid increase of molecular complexity through converting simple, cheap, and seldom exploited starting materials into polycyclic structures never described before, (2) the absence of chemical catalysts, (3) a very low energy input.

[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

“…The literature provides limited data on the preparation of pyrrolo[1,2- b ]oxazine derivatives [ 78 , 79 ], especially possessing an unsaturated pyrrole core [ 80 , 81 ]. Therefore, we elucidated the scope of the found transformation.…”

Hyperbaric reactions in organic synthesis. Progress from 2006 to 2021

“…One of the simplest highly nucleophilic enamines, 145 , can unexpectedly react with nitroarenes 144 at elevated pressure to form complex polycyclic structures 146 in excellent yields (Scheme 44). 93 It is most likely that, the mechanism starts with the nucleophilic addition of enamine 145 to the β-position of nitroarene 144 . The obtained intermediate (not shown) would then re-aromatize and cyclize, providing the unstable species 147 .…”

“…One of the simplest highly nucleophilic enamines, 145, can unexpectedly react with nitroarenes 144 at elevated pressure to form complex polycyclic structures 146 in excellent yields (Scheme 44). 93 the mechanism and provides the desired adduct 146. The stereochemistry of the single obtained diastereoisomer is presented in Scheme 44.…”

Introduction of Carbon Substituents into Nitroarenes via Nucleophilic Substitution of Hydrogen: New Developments

“…In 2018, it was shown that they can enter into such reactions with highly electrophilic nitroarenes, for instance nitroisoquinoline or m-dinitrobenzene, to form peculiar heterocyclic systems provided the reaction is carried out under high static pressure of 14 kbar (Scheme 39). 101…”