Inverse-Electron-Demand Reactions with Enamine-Activated Dienophiles

SCHEME 1.24 Organocatalytic hetero-Diels-Alder reaction. [Pg.14]

Inverse-electron-demand hetero-Diels-Alder reaction of enolizable aldehydes with a,P-unsaturatedketophosphonates [27], o-quinones [28], a-keto-a,p-unsaturated esters [29], a,P-unsaturated trifluoromethyl ketones [30], and o-benzoquinone diimide [31] was also reported. [Pg.14]

Inspired by dienamine catalysis in inverting the inherent reactivity of a,P-unsaturated aldehydes, which acted as nucleophiles for direct enantioselective y-amination with [Pg.14]

SCHEME 1,26 Aza-Diels-Alder reaction with alehydes by dienamine catalysis. [Pg.15]

Design of enamine-iminium cascades Examples of [4-1-2] reactions with enamine-activated dienes Inverse-electron-demand [4-1-2] reactions with enamine-activated dienophiles Enamine-iminium-enamine cascades... [Pg.1]

Inverse-Electron-Demand [4+2] Reactions with Enamine-Activated Dienophiles In contrast to the Barbas group s ingenious design of Diels-Alder reactions using enamine-activated dienes, Jprgensen envisioned that chiral enamines could act as electron-rich dienophiles and undergo an enantioselective inverse-electron-demand hetero-Diels-Alder reaction (Scheme 1.24) [26]. [Pg.13]

Even more so than 1,2,4-triazines (see p 441), 1,2,4,5-tetrazines display heterodiene activity in their reactions towards electron-rich, multiply-bonded systems. Enol ethers, enamines, ketene acetals, imido esters, alkynylamines and nitriles undergo [4+2] cycloadditions with inverse electron demand across the ring positions C-3 and C-6 [176]. Olefinic dienophiles lead to diverse products depending on their substituents ... [Pg.451]

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