Über Hopfenbitterstoffe, XII. Zur Kenntnis des 4‐Desoxy‐Humulons

Abstract

Hierbei stellt das Mo1.-Verhaltnis Ph1oracetophenon:Alkali = 1 : 1.5 einen Kom-promil3 dar zwischen der fur Di-alkylierung notwendigen Alkali-Menge einerseits, 1 ) XI.

The Chemistry of Hop Constituents

“…Five years later 4-desoxyhumulone was obtained crystalline, mp 83°, and characterized as the tribenzoate, mp 139° ( 292). Subsequently, it was isolated from Hallertau hops (1957 crop) in 0.02% yield (293).…”

“…Hydrolysis of the geminal dimethylphloracetophenone (LXII) gives filicinic acid (LXV-III) (330) in 5% over-all yield (299), but a more convenient synthesis of this compound consists of dimethylation of 2,4-diacetylphloroglucinoI (LXIX) followed by hydrolysis of LXX which affords filicinic acid from phloroglucinol (175). To revert to consideration of the hop resins, after preliminary experiments in which 3,5-dimethylphloracetophenone (LXI, R = R' = CH3) and 3,5-di(3methylbut-2-enyl) phloracetophenone (XXXV, R = CH3) were synthesized (292), 4-desoxyhumulone (XX-XV, R = f-Bu) was isolated in a crystalline form, mp 83°, and characterized as the tribenzoate, mp 139°, and by conversion to (± )-humulone (292). The alkylation was carried out in water using a molecular ratio of phlorisovalerophenone: potassium hydroxide: 3-methylbut-2-enyl bromide of 1:1.5:1.5, but the yield of 4desoxyhumulone was still only 9.75% (292).…”

“…To revert to consideration of the hop resins, after preliminary experiments in which 3,5-dimethylphloracetophenone (LXI, R = R' = CH3) and 3,5-di(3methylbut-2-enyl) phloracetophenone (XXXV, R = CH3) were synthesized (292), 4-desoxyhumulone (XX-XV, R = f-Bu) was isolated in a crystalline form, mp 83°, and characterized as the tribenzoate, mp 139°, and by conversion to (± )-humulone (292). The alkylation was carried out in water using a molecular ratio of phlorisovalerophenone: potassium hydroxide: 3-methylbut-2-enyl bromide of 1:1.5:1.5, but the yield of 4desoxyhumulone was still only 9.75% (292). By similar methods 4-desoxycohumulone, mp 89°( tribenzoate, mp 153°), and 4-desoxyadhumulone as an oil (tribenzoate, mp 127°) were obtained, the former in 2.7% yield (210).…”

Phloroglucinol compounds of natural origin: Synthetic aspects

“…79 Several other literature reports for the syntheses of humulones, their derivatives and analogues cite similar acylation and prenylation strategies. [80][81][82][83][84][85] 2.6.3 Syntheses of polyprenylated phloroglucinols. Several polycyclic polyprenylated acylphloroglucinols (PPAPs) have been reported from natural sources.…”

4-Desoxyhumulones in Hops

“…Brew (see above) were added. After evaporation to dryness the residue was silylated by methods (a) and (6). An additional sample (0-2 ml.)…”