Photochemical Reactions of α-Methoxy-β, γ-enones: Isolation of 1,2-acyl shift Intermediate and Synthesis of Versatile Precursors to Oxygenated Capnellanes

Molecular Complexity from Aromatics: A Novel, Stereoselective Route to Tricyclo[5.2.2.01,5]undecenones, Tricyclo[6.2.2.01,6]Dodecenones, and [n.3.3]Propellanes

“…The reduction of 13 with Raney Ni by a modification of the earlier method 22 gave the 4-hydroxymethyl-5-indanol 5a . Oxidation of 5a with aqueous sodium metaperiodate in the presence of ethyl acrylate according to a method developed in our laboratory 23c furnished adduct 14a in good yield, as a result of a regio- and stereoselective cycloaddition of the in situ generated spiroepoxycyclohexa-2,4-dienone 6a (Scheme ). The structure of adduct 14a was deduced from its 1 H NMR and 13 C NMR spectral data, COSY spectrum, and comparison.…”

One-Pot Transformation of Salicylaldehydes to Spiroepoxydienones via the Adler–Becker Reaction in a Continuous Flow

“… 18 , 19 In addition, due to their diverse chemical reactivity, spiroepoxydienones are valuable intermediates for the generation of complex molecular architectures ( Figure 1 C). 11 , 20 − 24 For example, when not protected, spiroepoxydienones (substituted in positions C-5 and C-6) can undergo Diels–Alder cycloaddition, forming cycloadducts by dimerization or in the presence of an external dienophile, providing a powerful methodology for the synthesis of compounds containing the bicyclo[2.2.2]octane ring system ( Figure 1 C) with a notable contribution by Singh and Johnson, among others groups. 11 , 13 , 22 Due to their versatility, spiroepoxydienones can be quite unstable in the presence of light since photochemical isomerization can occur forming the respective salicylaldehyde ( Scheme 1 ).…”

“…Synthesis of spiroepoxydienones via the Adler–Becker reaction (A) and application as a versatile intermediate for the total synthesis of bioactive compounds (B) and as a tool for molecular diversity (C). ,,,,− …”

“…Spiroepoxydienones are reported as key intermediates for the total synthesis of several bioactive natural products such as (−)-4-hydroxyzinowol, triptolide, platencin, ovalicin, and (+)-hirsutic acid (Figure B). , In addition, due to their diverse chemical reactivity, spiroepoxydienones are valuable intermediates for the generation of complex molecular architectures (Figure C). ,− For example, when not protected, spiroepoxydienones (substituted in positions C-5 and C-6) can undergo Diels–Alder cycloaddition, forming cycloadducts by dimerization or in the presence of an external dienophile, providing a powerful methodology for the synthesis of compounds containing the bicyclo[2.2.2]­octane ring system (Figure C) with a notable contribution by Singh and Johnson, among others groups. ,, Due to their versatility, spiroepoxydienones can be quite unstable in the presence of light since photochemical isomerization can occur forming the respective salicylaldehyde (Scheme ). ,, Despite the rich chemistry of the formed spiroepoxydienones, their instability under the oxidative reaction conditions as well as the broad instability of the starting salicylic alcohols limits the use of this valuable transformation as a robust synthetic methodology.…”