hohenackeri (Euphordiaceae), in addition to the known 3-epi-lupeol, two new triterpenes glochidone and glochidiol have been isolated and assigned structures I and VIIIa respectively. The stereochemistry of the hydroxyl groups in glochidiol has been determined by the partial synthesis of three of the fourpossiblestereoisomers of the dihydrodiol diacetate (Vd, VId and VIId) which all differ from dihydroglochidiol
ORD and CD studies on the structure of carbonyl derivatives of pentacyclic triterpenes
作者:J. Śliwowski、Z. Kasprzyk
DOI:10.1016/0040-4020(72)80159-5
日期:1972.1
A series of mono- and di-carbonyl derivatives of pentacyclic triterpenic alcohols have been investigated by ORD and CD methods. The effect on ORD and CD spectra of backbone type, position of double bond, position of carbonyl groups and position of additional acetoxyl groups was determined.
Lupan-3-one (5) was irradiated in n-hexane under an argon atmosphere using a high pressure mercury lamp. Besides three seco compounds, namely 10α-(2-formylethyl)-5β-isopropenyl-des-A-lupane (6), 10α-(2-carboxyethyl)-5β-isopropyl-des-A-lupane (8), and 10α-(2-carboxyethyl)-5β-isopropenyl-des-A-lupane (9), two seco-nor compounds, 10α-(carboxymethyl)-5β-isopropyl-des-A-lupane (7) and lactone of 10α-(carboxymethyl)-5α-hydroxy-5β-isopropyl-des-A-lupane (10), have been isolated and their structures have been determined. NMR signals of 10 were examined using Eu(fod)3-d27 as a shift reagent.
The chemistry of triterpenes and related compounds. Part XLVI. Some novel products from the ozonolysis of methyl acetylbetulinate
作者:R. T. Aplin、Rosalind P. K. Chan、T. G. Halsall
DOI:10.1039/j39690002322
日期:——
Ozonolysis of methyl acetylbetulinate (II) gives number of products in addition to the nor-ketone (V) formed by the normal fission of the isopropenyl double-bond. They include the Baeyer–Villiger oxidation product (VIII) of the nor-ketone and two trisnor-compounds. In one of these (XVIII) the isopropenyl group has been lost and a Δ18,19 double-bond has been formed at the carbon to which it was attached
Functionalisation of unactivated methyl groups through cyclopalladation reactions
作者:Jack E. Baldwin、Richard H. Jones、Carmen Najera、Miguel Yus
DOI:10.1016/s0040-4020(01)96448-8
日期:1985.1
through deuteriation or oxidation affords the expected products (21) and (31), or (22), (23), (24), and (32), respectively. The second palladation of the compound (22) takes place on the remaining methylgroup yielding the organopalladium derivative (26). Finally, -lupanone oxime is palladated selectively in the 23-position leading to the organopalladium compound (38); the transformation of this compound