ISSN:
0075-4617
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Preparation and Hydrolysis of 5-[3-Halo-2-propynylidene]-1,3-dioxolanes5-[3-halo-2-propynylidene]-1,3-dioxolanes 2a-c, e are synthesized by halogenation of 5-[2-propynylidene]-1,3-dioxolanes 1a, b, e with sodium hypochlorite or -bromite. Their hydrolysis yields 5-halomethyl-2,3-dihydrofuran-3-ones 4a-c, e, or open-chain 1,2-dihalo-1-penten-5-ol-4-ones 5a-e. These products are cyclized to 4a-c, e by sodium hydroxide and to 5-dialkylaminomethyl-2,3-dihydrofuran-3-ones 7a-f with sec. amines. The reduction of the ketoalcohols 5a and b with sodium borohydride gives the dihydroxy compounds 8a, b. 5a isomerizes in acidic solution to 1,2-dibromo-1-hexen-4-ol-5-one (9); on heating in absence of a solvent 5a dehydrobrominates to 2-bromo-2-hexene-4,5-dione (10). The bromine of the latter is readily substituted by sec. amines. On hydrolysis the 2-dialkylamino-2-hexene-4,5-diones 11-13 are cyclized to 2-hydroxy-2,5-dimethyl-2,3-dihydrofuran-3-one (15).
Notes:
Durch Halogenierung von 5-[Propin-(2)-yliden]-1.3-dioxolanen 1a, b, e mit Natriumhypohalogenit werden 5-[3-Halogen-propin-(2)-yliden]-1.3-dioxolane 2a-c, e dargestellt. Deren Hydrolyse führt zu 5-Halogenmethyl-2.3-dihydro-furanonen-(3) 4a-c, e oder zu offenkettigen 1.2-Dihalogen-penten-(1)-ol-(5)-onen-(4) 5a-e. Diese werden durch Natriumhydroxid zu 4a-c, e, durch sekundäre Amine zu 5-Dialkylaminomethyl-2.3-dihydro-furanonen-(3) 7a-f cyclisiert. Mit Natriumborhydrid liefern die Ketoalkohole 5a, b die Dihydroxy-Verbindungen 8a, b. 5a ist in saurer Lösung zum 1.2-Dibromhexen-(1)-ol-(4)-on-(5) (9) umzulagern; beim Erhitzen ohne Lösungsmittel entsteht 2-Brom-hexen-(2)-dion-(4.5) (10), dessen Brom durch sekundäre Amine substituierbar ist. Die 2-Dialkylamino-hexen-(2)-dione-(4.5) 11-13 werden bei der Hydrolyse zu 2-Hydroxy-2.5-dimethyl-2.3-dihydro-furanon-(3) (15) cyclisiert.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.19717520118
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