Diastereodivergent formal [4 + 1] cycloaddition of azoalkenes as one-carbon synthons

Catalytic [2,3]-sigmatropic rearrangement of sulfonium ylides derived from azoalkenes: non-carbenoid Doyle–Kirmse reaction

“…12 Very recently, our group has developed a diastereodivergent formal [4+1] cycloaddition reaction of azoalkenes with p -quinone methides via a domino oxa-1,4-addition/1,6-addition process, which allowed the use of azoalkenes as a carbene-like one-carbon (C1) synthon. 13 Along this line and with our continuous interest in the facile synthesis of nitrogen-containing compounds, 14 herein, we report the Sc( iii )-catalyzed [2,3]-sigmatropic rearrangement of sulfonium ylides derived from azoalkenes (Scheme 1b). Under the catalysis of Sc(OTf) 3 , the addition of allylic (propargylic) thioethers 2 to electron-deficient azoalkenes 1 yielded zwitterionic intermediates Int-1 .…”

Assembly of Dihydropyridazines via [4+2] Cycloaddition of In Situ Generated Azoalkenes

“…In recent years, azoalkenes have been extensively used as efficient intermediates for the synthesis of various nitrogencontaining heterocycles, [9][10][11][12][13][14][15][16][17][18][19][20][21] and a broad range of transformations has been established using azoalkenes as suitable chemical handles. [22][23][24][25] In 2014, the Wang group disclosed a catalytic asymmetric inverse electron-demand aza-Diels-Alder reaction of labile electron-deficient azoalkenes with electronrich alkenes, providing pyridazines with excellent enantioselectivities.…”

Functionalized Chromans from ortho-Quinone Methides and Arylallenes

“…ortho -Quinone methides ( o -QMs; 1 ) and allenes ( 2 , Scheme ) , are two classes of reactive intermediates which have been utilized in organic synthesis for various natural and synthetic compounds. Both ortho - and para -quinone methides ( o - and p -QMs) have found their use in various types of reactions such as formal [4 + n ]-cycloaddition/cyclization reactions, nucleophilic additions, oxa-Michael/1,6-additions, oxa-6π-electrocyclizations, many of which also in asymmetric manner, among others. , Allenes have drawn much attention from organic chemists for their unique physical-organic as well as chemical properties, thus prompting the development of various synthetic methods for their preparation . Moreover, numerous natural products also contain allene as their functional group .…”