Chemistry of 1,3-dioxepins. XII.' 4,7-dihydro-5-nitro-1,3-dioxepins in the Diels-Alder reaction with 4-methyloxazole

Scientific paper - Original scientific paper

• Author: Milena Jadrijević-Mladar Takač
• Author: Ivan Butula; MBZ: 6372
• Author: Mladen Vinković
• Author: Miljenko Dumić
• Author's institution: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of medicinal chemistry)
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract (english)

4,7-Dihydro-5-nitro-l,3-dioxepins 4' prepared by dehydrohalogenation
of vic-chloronitro-dioxepanes 2 and/or dehydrohalogenationdemercuration of vic-chloromercurynitro-dioxepanes 3 represent reactive dienophiles in the Diels-Alder cycloaddition with 4-methyloxazole (5), giving pyridoxine (8) intermediates 1,5-dihydro-9-hydroxy- 8-methyl-3H-[1,3]dioxepino[5,6-c]pyridines 6 in poor yields. The side products of this reaction were 4,7-dihydro-4-hydroxyimino- 6-nitro-l,3-dioxepins 7, the structure of which was confirmed by parallel synthesis, i.e. by nitrosation of 4 with ethyl nitrite. The order of reactivity in the series of 5-substituted-4, 7-dihydro- 1,3-dioxepins, calculated by AMI semiempirical method, is predicted to be 5-nitro- > 5-unsubstituted- > 5-cyano- > 5-chloro-4,7-dihydro- 1,3-dioxepin, and it is in agreement with experimental data.

• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Croatica Chemica Acta
• Numbering: vol. 70, no. 2, pp. 649-666
• p-ISSN: 0011-1643
• e-ISSN: 1334-417X
• URN:NBN: urn:nbn:hr:163:555276
• Publication: 1997
• Document URL: https://hrcak.srce.hr/176964
• Type of resource: Text
• Access conditions: Open access
• Created on: 2020-04-29 12:43:06