A common variety of Myopovum deserti A. Cunn. (Ellangowan Poison Bush) yields an essential oil consisting largely of the iridoid monoterpene, (1R)-1-methoxymyodesert-3-ene, C11Hls02, (1 R,4aS,7R,7aR)-1-methoxy-4,7-dimethyl-l,4a,5,6,7,7a-hexahydrocycopenta[c]pyran, b.p. 6772 mm, [@lo -165'. This cyclic acetal is hydrolysed to methanol and a mixture of two epimeric cyclopentanoid dialdehydes which are oxidized to the two epimeric trans,trans-nepetalinic acids and yield (+)-(R)actinidine with Brady's reagent. (1R)-1-Methoxymyodesert-3-ene is oxidized by ozone/hydrogen peroxide to (1R,2R,5R)-2-acetyl-5-methylcyclopentanecarboxylic acid.Hydrogenation yields mainly (1R)-methoxymyodesertan, hydrolysed by aqueous maleic acid at room temperature to methanol and a cyclic hemiacetal, (lR,4R,4aR,7R,7aR)-4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta[c]pyran-1-01, Oxidation of this cis&-hemiacetal by bromine in acetate buffer yields a lactone further oxidized by chromic acid to (2R,1'S,2'R,3'R)-2-(2'-carboxy-3'-methylcyclopentyl)propionic acid.(1R)-1-Methoxymyodesertan, refluxed with aqueous phthalic acid, yields (+)-(4R,4aR,7R)-4,7-dimethyl-3,4,4a,5,6,7-hexahydrocyclopenta[c]pyran. Treatment of the hexahydropenta[c]pyran, the cis,cis-hemiacetal or (1R)-1-methoxymyodesertan with hydrochloric acid yields a tvans,transhemiacetal, (1 R,4R,4aR,7R,7aS)-4,7-dimethyl-1,3,4,4a,5,6,7,7a-octahydrocyclopenta[c]pyran-l-ol, which equilibrates in solution to a mixture of a-and j3-anomers. Spectral studies of these and other products establish the configuration of the natural product at C 1.(1R)-1-Methoxymyodesert-3-ene is not toxic to sheep as are the j3-substituted furans characteristic of most other chemovarieties of M. desevti.The shrub Myoporum deserti A. Cunn. (Ellangowan Poison Bush), which is found in the drier areas of Australia, is a well authenticated stock poison.' Previous parts2 of this series have described the isolation and chemistry of 11 toxic furanoid sesquiterpene ketones, such as (1) and (2), from various chemovarieties of the species but certain others contain iridoid monoterpenes accompanied by little or none of the toxic furanoid derivatives.
The synthesis of several analogues of the chloralformamide fungicides is reported. The compounds, which comprise N-methyl-N-(2,2,2-trichloro- 1-arylaminoethyl)formamides and related alkoxyethyl and aryloxyethyl derivatives, exist at room temperature as two isomers due to restricted rotation about the C-N amide bond. The results of their evaluation as fungicides are reported.
The structures of the N-benzoyl derivatives of aziridine, azetidine, pyrrolidine, piperidine, hexamethyleneimine and heptamethyleneimine in solution have been investigated by 13C n.m.r. spectroscopy. In conjunction with literature crystal structure and dynamic intramolecular exchange data, it has been concluded that N-benzoylaziridine and N-benzoylazetidine possess pyrimidal nitrogen atoms in solution. The N-benzoyl derivatives of pyrrolidine, piperidine, hexamethyleneimine and heptamethyleneimine have planar or near planar nitrogen atoms.
A further chemovariety of Myoporum deserti A. Cunn. yields an essential oil consisting predominantly of theiridoid hemiacetal esters, (+)-(I R)-and (-)-(1s)-1-acetoxymyodesert-3-ene. Hydrolysis of either ester yields (1S,2R,5R,1'~)-2-(1'-formylethyl)-5-methylcyclopentane-l-carbaldehyde and acetic acid or, in the presence of Brady's reagent, the bis-2,4-dinitrophenylhydrazone of the 1 Repimer. The stereochemistry at C 1 of the esters follows from the close correlations in 'H and 13C n.m.r. spectra and 0.r.d. curves of the (-)-ester and the ether (-)-(1R)-1-methoxymyodesert-3-ene. Hydrogenation of the esters in methanol yields mainly myodesertan, (4s)-myodesertan, (1R)-1methoxymyodesertan and (lR, 4s)-1-methoxymyodesertan and usually no acetates. Acetolysis of (1R)-1-methoxymyodesertan even under mild conditions yields (lR, 7aS)-and (IS, 7aS)-1-acetoxymyodesertan with trans rather than cis ring junctions.In 1966, Park and Sutherland briefly reportedi that the essentiai oil from some specimens of the stock-poisoning shrub, Myopovum desevti A. Cunn growing near Mitchell, Qld. differed from others2-' in yielding dialdehyde (la)' and a substance, b.p. 84' 11 mm, for which a plane structure similar to that of nepetalactone (2) was suggested. An iridoid acetal, (-)-(1R)-1-methoxymyodesert-3-ene (3) which readily *
The torsional angles in 30 N-substituted benzamides and related compounds have been estimated by the use of the 13C substituent chemical shifts of the meta and para carbon atoms. Steric interaction between the N-substituted groups and the ortho hydrogen atoms of the benzene ring is the major determinant of non-planarity in these systems. A linear relationship between steric substituent constants of the N-substituted groups of some benzamides and the torsional angles is proposed. Dynamic processes involving rotation about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic steric effect to the overall steric interaction. The preferred conformations of some N-substituted groups is also discussed.
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