1,3‐ and 1,2‐Carbo‐Migration of 2‐Vinylbicyclo[2.2.2]octenols: Facile and Concise Synthesis of Bicyclo[4.2.2]/[3.2.2] Skeleton by Two/One‐Carbon Ring Expansion

Abstract

The synthesis of a series of bicyclo[4.2.2]octenones and bicyclo[3.2.2]heptenones by 1,3- or 1,2-migration reaction from 2-vinylbicyclo[2.2.2]octenols is reported. These ring-expansion reactions were accomplished under basic or neutral conditions. Whether 1,3- or 1,2-migration takes place depends on endo- or exocyclic olefin displacement in the substrates.

Photochemistry of Tricyclo[5.2.2.02,6]undeca‐4,10‐dien‐8‐ones: An Efficient General Route to Substituted Linear Triquinanes from 2‐Methoxyphenols. Total Synthesis of (±)‐Δ9(12)‐Capnellene

“…This phenomenon has been reported previously in the literature. [5] The regiochemistry of all the isolated tricyclo[5.2.2.0 2,6 ]undeca-4,10-dien-8-ones 3 were elucidated by ]undeca-4,10-dien-8-ones also proved the endo stereochemistry and regiochemistry of 3. The single-crystal Xray diffraction analysis further confirmed the structure of 3 f (Figure 1 ]undeca-4,10-dien-8-ones without the dimethyl ketal moiety adjacent to the carbonyl group were also prepared for comparison of their photochemistry.…”

“…Similarly 7 b-d were isolated in 10-24 % yields from direct irradiation of tricyclo[5.2.2.0 2,6 ]undeca-4,10-dien-8-ones 3 b-d over a short time period (0.5-3 h) ( Table 3). On the other hand, upon irradiation for a prolonged period (64-149 h), 3 b-d gave the decarbonylated products 8 b-d as the sole products.…”

“…[4] Accordingly, we carried out the Diels-Alder reactions of cyclopentadiene with masked o-benzoquinones 2 that were generated in situ by the addition of a solution of a 2-methoxyphenol 1 in methanol to a mixture of diacetoxyiodobenzene and cyclopentadiene in refluxing methanol to afford tricyclo[5.2.2.0 2,6 ]undeca-4,10-dien-8-ones 3 in high yields (Table 1). Products 3 were formed exclusively under these conditions, except in the case of masked o-benzoquinones 2 a and 2 c, which gave both possible adducts, that is, 3 a and 4 a, and 3 c and 4 c, respectively.…”

“…[3] Abstract: An efficient and short entry to polyfunctionalized linear triquinanes from 2-methoxyphenols is described by utilizing the following chemistry. The Diels-Alder reactions of masked obenzoquinones, derived from 2-methoxyphenols, with cyclopentadiene afford tricyclo[5.2.2.0 2,6 ]undeca-4,10-dien-8-ones. Photochemical oxa-di-pmethane (ODPM) rearrangements and 1,3-acyl shifts of the Diels-Alder adducts are investigated.…”

“…[5][6][7][8][9][10][11][12][13] Among these, bicyclo-A C H T U N G T R E N N U N G [2.2.2]octenones bearing the b,g-unsaturated carbonyl chromophore are suitable for ODPM rearrangement and can be used as precursors to generate quinane skeletons. There has been considerable interest in the photochemical reactions of b,g-unsaturated ketones.…”