A [4.5.5.5]Fenestrene via intramolecular enone-alkyne photocycloaddition

An Expeditious and Atom‐Economical Synthesis of a New Generation of Substituted [4.6.4.6]Fenestradienes

“…[2] Toward these ends, we have focused our attention on developing facile routes to unusual scaffolds to prepare structurally diverse materials of potential theoretical and biological value. [5] Intramolecular arene-olefin photo-cycloadditions, [6] photoinduced [2+2] cycloadditions, [7] transition-metal-induced cyclizations, [8] and cascade cyclizations [9] are some of the powerful methods that have been used to generate this class of compounds. [4] Several syntheses of fenestranes have been reported and since the appearance of the earliest contributions in this field, access to these compounds has improved in terms of the number of steps required and overall yield.…”

“…[4] Several syntheses of fenestranes have been reported and since the appearance of the earliest contributions in this field, access to these compounds has improved in terms of the number of steps required and overall yield. [5] Intramolecular arene-olefin photo-cycloadditions, [6] photoinduced [2+2] cycloadditions, [7] transition-metal-induced cyclizations, [8] and cascade cyclizations [9] are some of the powerful methods that have been used to generate this class of compounds.…”

Synthesis and Structure of [4.5.5.5]Fenestranes ( = tetracyclo[5.4.1.04, 12.09, 12]dodecanes)

“…The structural relationship between 5 and the product prepared by hydrogenation of 9 (+ 5) was established by comparison of 7b and the product obtained from hydrogenation of lob. NOE Measurements with 10b revealed the cis-relationship of H-C(4), H-C(9), and H-C(10) [3]. The AcO and the COOEt group are, therefore, cis to each other.…”

“…NOE Measurements with 10b revealed the cis-relationship of H-C(4), H-C(9), and H-C(10) [3]. The AcO and the COOEt group are, therefore, cis to each other.…”

“…Reduction of 5 with NaBH, occurred stereoselectively and gave 7a, from which 7b was obtained. The latter material was identical with material prepared by hydrogenation of 10b which was obtained from 9 [3] via 10a. Reduction of 6 with NaBH, gave 8a as a single isomer, whereas reaction of 6 as well as of 8a with LiAlH, gave the crystalline diol 8b.…”