DTHDA Reaction with Heterodienophiles

R = Me, 76%). The second DA reaction with Ph-TAD gave bis-adduct 115 (R = H, 87%) by approaching from the less-hindered convex it-face. 

Brummond et al. reported that the amino acid-derived cross-conjugated triene bearing an acrylate dienophile 116, which was synthesized via Rh(I)-catalyzed allene Alder-ene reaction and introduction of the dienophile moiety, underwent 

In summary, the DTHDA protocol is an efficient and attractive method for stereoselective synthesis of a variety of complex ring-fused heterocyclic systems. 

(a) 2-(Acetylaminomethylene)propanedial (80a) was prepared by the reaction of triformyhnethane with acetamide in the presence of BF3 OEt2 Budfeinsky, 

Commun., 56, 1019—1031 (c) 2-(Arylmethylene)propanedials (SOd, e) were prepared according to the known method Arnold, Z, Krai, V., and Dvorak, D. (1982) Tetrahedron Lett., 23, 1725-1726 (d) Dvorak, D., 

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Cadogan et al. [27] reported the DTHDA cycloaddition of parent cross-conjugated carbotriene ([3]dendralene) 106 with some representative electron-withdrawing dienophiles including heterodienophiles (Scheme 2.16). They applied a flash vacuum pyrolysis technique to synthesize parent carbotriene 106 in pure form from 3-vinyl-3-sulfolene. The initial DA reaction with p-benzoquinone (PBQ) at 40 °C afforded mono-adduct 107 (90%), followed by the second HDA reaction with Ph-TAD at 40 °C to provide the mixed bis-adduct 108 (63%). Triene 106 gave mono-adduct 109 in the presence of even an excess amount of TCNE at 40 °C. Ph-TAD was able to react with mono-adduct 109 at 40°C to provide crossed bis-adduct 110 (63%). Bis-adduct 111 was directly obtained (21%) by reaction of 106 with excess Ph-TAD at 40 °C, as same as the reaction with Ph-MI. 

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