Ozonolyses of (−)-β-pinene (1) and of (+)-sabinene
(6)
in the gas phase afforded the corresponding ozonides
6,6-dimethylbicyclo[3.1.11,5]heptane[2-spiro-3]-1,2,4-trioxolane (2) and
5-isopropylbicyclo[3.1.01,5]hexane[2-spiro-3]-1,2,4-trioxolane (7), which were isolated as mixtures
of
two diastereomers each. Major products were the
corre
sponding ketones
6,6-dimethyl-2-oxobicyclo[3.1.11,5]heptane
(3) and
5-isopropyl-2-oxobicyclo[3.1.01,5]hexane
(8). Additional
products were the lactones 7,7-dimethyl-2-oxa-3-oxobicyclo[4.1.11,6]octane (4) and
7,7-dimethyl-3-oxa-2-oxobicyclo[4.1.11,6]octane (5) derived from
β-pinene (1) as well
as
6-isopropyl-2-oxa-3-oxobicyclo[4.1.01,6]heptane
(9) and
6-isopropyl-3-oxa-2-oxobicyclo[4.1.01,6]heptane
(10) derived from sabinene (6).
Ozonolyses of a-0x0-alkenes: On the Existence of a-0x0-ozonidesOzonolyses of nine acyclic (la-i) and of two cyclic (14, 29) a-0x0-alkenes on polyethylene or in pentane afforded in eight cases (1 d -i, 14, 29) isolable a-0x0-ozonides. a-Diozonides (9) are obtained from five of the acyclic a-0x0-alkenes (1 a, b, d, g, h). All isolated ozonides are labile; the 2,4-dinitrophenylhydrazones of the a-0x0-ozonides, however, are very stable. Decomposition of the a-0x0-ozonides affords not only the hitherto known fragments, but non-peroxidic isomers (8) of the ozonides, too.Bei Urnsetzungen von acyclischen a-0x0-alkenen (1) mit Ozon in inerten Losungsmitteln wurden in den meisten F11-len nicht die entsprechenden Ozonide 6, sondern ganz uberwiegend die entsprechenden Bruchstiicke 3 und 7 erhalten '). Ausnahmen davon sind die Ozonolysen von l e und l i in Pentan, wobei jeweils das Ozonid 6e erhalten, jedoch nicht als Reinsubstanz isoliert wurde2), sowie die Ozonolyse von l a in CC14, wobei das Ozonid 6a postuliert, jedoch nicht eindeutig nachgewiesen wurde3). Auch bei der Ozonolyse von cyclischen a-0x0-alkenen wurden in der Mehrzahl der Falle anormale Spaltprodukte erhalten ' ! Ausnahmen davon sind die Ozonolysen von einigen 2,3-disubstituierten Indenonen, welche isolierbare Ozonide lieferten4).Die Bildung der anomalen Spaltprodukte 7 kann a priori auf zwei Arten erklart werden, namlich entweder durch intramolekulare Baeyer-Villiger-Oxidation der Zwitterionen 2 R'
Gas‐phase ozonizations of 1,2‐dimethylcyclopentene (1) and of 2,6‐heptanedione (5) afforded in each case dimethylcyclopentene ozonide (2) in low yields. In the ozonization of 1, diketone 5 was formed as the single major product, along with nine “abnormal” ozonolysis products which were formed by oxidative cleavage of carbon−carbon single bonds.
Treatment of 1,2,4,5-tetramethyl-1,4-cyclohexadiene (1) on polyethylene and in pentane with excess ozone afforded mixtures of the oxydehydrogenation product 2 and of the The hitherto unknown oxydehydrogenation of 1 by ozone is not restricted to reactions in the protic solvent methanol.[a]
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