The interactions of singlet oxygen with 1-vinylcycloalkenes after P(OEt)(,3) reduction led to 1,2-dioxins 1 via 1,4-cycloaddition, secondary diene alcohols 3 by the "ene" reaction pathway and trans- and cis-1,2-dioxin alcohols 4 and 5 by further 1,4-cycloaddition of ('1)O(,2) to 3. Small amounts of competitive "ene" reaction product, the tertiary diene alcohols 2, were obtained only in the case of medium size rings (n = 9, 10 and 12). The stereochemistry of the various products was elucidated by NMR spectrometry. The product ratios showed that five and seven membered ring semicyclic dienes undergo predominantly the "ene" reaction. As ring size increases, 1,4-cycloaddition competes closely with the "ene" process, the crossover point being at ring size ten. The six membered ring semicyclic diene was an exception, 1,4-cycloaddition for this compound surpassing the "ene" reaction. The above results held also when 1-isopropenylcycloalkenes were used as substrates. Possible explanations in terms of the conformations of the alicyclic rings are presented. The predominant formation of secondary diene alcohols (Markovnikov directive effect) in the "ene" reaction process excluded the participation of a concerted ene mechanism involved in the semicyclic 1,3-diene systems. / The 1,2-dioxins and 1,2-dioxin alcohols (except those derived from five membered semicyclic dienes) were converted to furans on treatment with FeSO(,4) and successful syntheses of (R)-menthofuran, (R)-evodone and ((+OR-)) chromolaenin were accomplished. Thus, the ('1)O(,2)-FeSO(,4) sequence for the transformation of semicyclic 1,3-dienes into cyclic furanoterpenoids may indeed have biogenetic significance. / Source: Dissertation Abstracts International, Volume: 45-04, Section: B, page: 1196. / Thesis (Ph.D.)--The Florida State University, 1984.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75319 |
| Contributors | JUO, ROUH - RONG., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 173 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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