Double Dehydro‐Diels–Alder Reactions of 1,5‐Dien‐3‐ynes

Abstract

Allene towards efficiency: Two new rings, six stereocentres and four CC bonds are generated in synthetically useful yields by double dehydro‐Diels–Alder reactions of readily available 1,5‐dien‐3‐ynes and alkenic dienophiles. Computational studies support a mechanism for this often highly stereoselective process involving two concerted cycloaddition events and a 1,2‐cyclohexadiene intermediate (see scheme).

Recent Progress in Dehydro(genative) Diels–Alder Reaction

“…In 2010, Sherburn and coworkers developed ad ouble dehydro-Diels-Alder reaction of 1,5-dien-3-ynes and alkenic dienophiles, in whicht he two central carbonso f1 ,5-dien-3-ynes participate in both cycloadditions to give polycyclic rings in synthetically useful yields (Scheme 13). [15] Only the endo,endo,syn-isomer of the bis-adducts was formed. Similard ouble dehydro-Diels-Alder reactions of 1,5-dien-3-ynes had been described previously, [16] but the yields were very low.B ased on density functional theory calculations, am echanismw as proposed involvingt wo concerted reactions anda1,2-cyclohexadiene intermediate.…”

Direct Cross‐Couplings of Propargylic Diols

“…1,1,4,4-tetraphenylbut-2-yne-1,4-diol, 4 1,1'-(ethyne-1,2-diyl)bis(cyclopentan-1-ol), 5 1,1diphenylbut-2-yne-1,4-diol, 6 and 4-methylpent-2-yne-1,4-diol 7 were prepared according to literature procedures.…”

“…4 Accordingly, numerous techniques to synthesize the 1,3-diene motif featuring various substitution patterns have been devised. [5][6][7][8][9][10][11][12][13] Cross-coupling reactions grant facile access to many butadiene substitution patterns. Thus, Böhmer and Grigg employed two-fold Stille or Suzuki-Miyaura reactions to convert propargylic dicarbonates into 2,3-diaryl-1,3-butadienes carrying up to two additional substituents (Scheme 1a).…”