An Efficient Synthesis of 6‐oxa‐spiro[3.4]octan‐1‐one Derivates Through 3‐diazochroman‐4‐one and Alkene

Abstract

Spiro[2,bicyclo [4.2.0]octane]-7'-one with fused and spirocyclic oxygen-containing rigid skeleton structure is obtained via Wolff rearrangement and cycloaddition with good yields. Then Spiro[2,2-dimethyl-benzofuran,hexahydro-isobenzofuran]-7'-one is synthesized by further Baeyer-Villiger oxidation. These two kinds of products have a special fused and spirocyclic oxygen-containing rigid skeleton structure and are reported by our group.

Strigolactone Analogues Derived from Dihydroflavonoids as Potent Seed Germinators for the Broomrapes

“…For the synthesis of 2-alkyl-substituted 4-chromanone derivatives 18a−24a, pyrrolidine-catalyzed cyclization of 2hydroxyacetophenone with aliphatic aldehydes or ketones readily afforded the desired products via a known Mannich procedure. 29 The coupling of compounds 18a−24a with ethyl formate using potassium tert-butanoate (tBuOK) as the base successfully yielded the enol intermediates, which were subsequently converted into the target SL analogues 18−24 upon condensation with 5-bromo-3-methyl-2(5H)-furanone in the presence of t-BuOK (Scheme 2b). The E-configuration was determined to be major isomers for these SLs based on the analysis of NOESY spectra.…”

“…1 H and 13 C NMR and HRMS spectra of all synthesized compounds were recorded on a Bruker AvanceII400 MHz spectrometer and Agilent 6520 Q-TOF LC/MS, respectively. The starting dihydroflavone derivatives 1a – 17a were prepared from the corresponding aromatic aldehydes according to the previously reported methods. , The dihydroflavone derivatives 18a – 24a and the corresponding enol intermediates were synthesized according to the previously described methods. − The enol intermediate 25b , 5-bromo-3-methyl-2­(5 H )-furanone, and rac -GR24 , were prepared according to the previously reported procedures.…”

Preparation and Synthetic Applications of Five-to-Seven-Membered Cyclic α-Diazo Monocarbonyl Compounds

“…The Wolff-rearrangement-derived ketenes can interact with more than nucleophiles. For instance, ketenes derived from 3-diazochroman-4-one ( 35 ) can undergo [2 + 2] cycloaddition with various olefins delivering 6-oxospiro[3.4]octan-1-ones 36 [ 51 ]. The presence of the catalyst is necessary to suppress a competition 1,2-alkyl migration, which would lead to 4-benzopyrans 37 .…”

Metal-free aminofluorination of α-diazo 2H-benzopyran-4-one: convenient access to β-fluoramides

“…Over the last few years, we have studied the reaction of α-diazo 2 H -benzopyranone compounds. 8 Herein, we report a tandem fluorination/Ritter reaction to synthesize β-fluoramides using 2 H -benzopyran-4-one compounds under metal-free catalytic conditions. Selectfluor was used as the electrophilic fluoride source in acetonitrile to build the β-fluorinated quaternary carbon center and amide derivatives of 2 H -benzopyran-4-one in one step, in which the solvent was involved as a nucleophile (Ritter-type reaction 9 ).…”