One‐Pot Assembly of 7‐Methylene‐6,8‐dioxabicyclo[3.2.1]octanes, Congeners of Frontalin, from Ketones and Acetylene

Abstract

A facile, consecutive, self‐consisting assembly of two molecules of ketones with two molecules of acetylene to afford 7‐methylene‐6,8‐dioxabicyclo[3.2.1]octanes, which are unknown congeners of widespread insect pheromones, has been discovered. The reaction is realized in a one‐pot procedure in a MOH/DMSO system (M = K, Cs) at 80 °C for 1 h under acetylene pressure or under atmospheric pressure; the isolated yields of the bicycles reached 86 %. The new reaction conceptually contributes to the synthesis of insect pheromones as well as to the chemistry of ketones and acetylene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Two classes of heterocycles—6,8‐dioxabicyclo[3.2.1]octanes and cyclopentenols from the same reagents: A quantum‐chemical comparison of mechanism

“…According to quantum‐chemical calculations, the R,R,S ‐diastereomers (or optical antipodes S,S,R ‐diastereomers) of 7‐methylene‐6,8‐dioxabicyclo[3.2.1]octanes are kinetically and thermodynamically more favorable. This coincides with the experimental observations that only dioxabicyclooctane diastereomer is formed in the reaction of ketones with acetylene.…”

Synthesis of Functionalized 3,4‐Dihydropyrans via Rearrangement of the Products of a One‐Pot Diastereoselective Assembly of Ketones and Acetylene

“…Indeed, these compounds are assembled as one diastereomer only. [8] Consequently, dihydropyrans 3a-g retain the stereochemistry of the precursors 2: in their NMR spectra, 1 H and 13 C signals of only one diastereomer are discernible (no signals doubling).…”

“…Recently, we have found [8] that the reaction of alkyl aryl ketones 1 with acetylene in the superbase systems MOH/ DMSO (M = K, Cs, 80°C, 1 h, initial acetylene pressure 12-14 atm) affords, instead of the expected acetylenic alcohols (classic Favorsky reaction), [9] 7-methylene-6,8-dioxabicyclo[3.2.1]octanes 2, close congeners of well-known insect pheromone frontalin, [10] as the only products in up to 86 % isolated yields (Scheme 1). dropyrans in excellent yields.…”

Polycyclic bridgehead acetals with enol functionality: one-pot assembly from aliphatic ketones and acetylene in KOH/DMSO suspension

“…10 Notably, enol ethers and cyclic acetals are well established widely used multi-purpose building blocks for organic synthesis and monomers. 11 The enol ether functionality and the acetal moieties are key structural units of diverse life-sustaining compounds such as polysaccharides, 12 In view of that alkyl-substituted frontalin derivatives are much structurally closer to natural representatives of these pheromones as compared to the corresponding aryl-substituted 18 we have attempted to implement the one-pot self-organization reaction of aliphatic and cycloaliphatic ketones 1a-j with acetylene, which might deliver an essentially new family of the above-mentioned polycyclic bridgehead acetals 2.…”