Nitroethylene as a versatile ketene equivalent. Novel one-step preparation of prostaglandin intermediates by reduction and abnormal nef reaction

Masked Ketenes as Dienophiles in the Diels–Alder Reaction

“…[63] However, despite the advantage of their higher DA reactivity, nitroalkenes as ketene equivalents frequently suffer from difficulties associated with the Nef reaction. [64][65][66][67] Nevertheless, successful reports in the context of target-oriented synthesis are known (Scheme 8).…”

Applications of Helical‐Chiral Pyridines as Organocatalysts in Asymmetric Synthesis

“…The impetus for this study is to fill a gap in the methodologies for the catalytic asymmetric Diels‐Alder reaction that can open ready access to cyclopentenes with multiple contiguous quaternary stereocenters, a motif that is found in medicinally relevant complex natural products (Figure 5). [19] The Diels‐Alder reaction of cyclopentadiene and nitroethylene, followed by ring‐opening, is a known strategy for the synthesis of highly substituted cyclopentenes () [20,21] …”

The inverted ketene synthon: a double umpolung approach to enantioselective β2,3-amino amide synthesis

“…Owing to the polarity with which the carbon–carbon bond is formed, the strategy constitutes a double umpolung: both C–C and C–N bonds are formed umpolung relative to the most common approaches to construction of the acyl component 22. Importantly, this umpoled C–N bond formation could allow enantioenriched β-amino amides with acidic α-chiral carbons to be prepared, endowing polarity-inverted ketene equivalence to nitroalkenes 23…”

“…Several reports of nitroalkane additions to nitroalkenes have appeared since Du's 2006 Zn( ii )/Ti( iv ) catalyzed additions of nitroethane,24 including organocatalyzed25 and metal-mediated transformations 23,26,27. The reaction's development has been driven mostly by interest in simple 1,3-diamines,28 and focused applications are all but absent 23,29.…”