atom must be such that the centers H-C@)-C(a)-C-0-0 in the hydroxy-hydroperoxy diradical can assume a cyclic arrangement. Table 3 shows a number of cases studied so far, in which a cyclic ketone is converted to an unsaturated carboxylic acid containing an additional oxygen atom. With the exception of (62), all the ketones contain a CH3-substituent a to the carbonyl group. In these examples the new C=C double bond, which is formed together with the carboxyl group, is always terminal.
Scope of the ReactionConsequently, this new photo-oxidation can be used as a step in the partial synthesis of 3,4-seco-triterpenecarboxylic acids with a A4 (23)
Die Reaktion des R3SiNSNSiR3 (1) [R = CH3] mit Chlor führt zum R3SiNSNCl (3). Mit Trifluoracetylchlorid erhält man aus 1 CF3CO(S3N3) und mit Schwefeldichlorid S(NSNSiR3)2 (5), welches sich mit weiterem Schwefeldichlorid unter Ringschluß zu S4N4 umsetzt. Eine günstige Darstellungsmethode für S(NSiR3)3 (6) wird mitgeteilt. Durch ESCA‐Spektren werden die Bindungsverhältnisse in 5 zu ermitteln versucht.
XI According toTLC (silica gel. solvent mixture CH,CI,:n-hexane 1 :3. staining in an iodine chamber) for A a spot was found at R, = 0.35. for B a spot at R, = 0.15. in addition to small initial spots.[9] The degree of deuteration of 95% of the [D,]DHA leads to the main components C
The H atoms and not the Si atom of the SiH3 groups coordinate to two of the eight Na atoms in [Na8(OC2H4OC2H4OCH3)6‐(SiH3)2]. Shown here is the novel Na8O6 polyhedron containing the two SiH3 groups. The surfaces of the Na8 cube are capped by oxygen atoms. Ab initio calculations on a suitable model showed that the inverted coordination mode is indeed energetically more favorable.
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