The crystal structure of coclaurine hydrobromide monohydrate and the absolute configuration of coclaurine.
Abstract The structure and absolute configuration of coclaurine has been determined by X-ray analysis of its hydrobromide monohydrate. The (+)-enantiomer has the D-configuration. The chirality of the molecular structure is correlated with circular dichroism measurements.
1-Benzyl-1,2,3,4-tetrahydroisoquinoline alkaloids from Alseodaphne archboldiana (Allen) Kostermans (family Lauraceae)
The alkaloids of Alseodaphne archboldiana (Allen) Kostermans of the family Lauraceae are 1-benzyl-1,2,3,4-tetrahydroisoquinolines, and they have been shown to be (-)-N-norarmepavine, (+)-reticuline, and both (+) and (-)-coclaurine. (+)-Coclaurine isolated from Xylopia papuana has been shown to be close to optical purity, and comparison with it indicates that the mixture of coclaurine optical isomers from A. archboldiana consists of (+)-coclaurine and (-)-coclaurine in the approximate ratio 3 : 1. Useful structural information can be derived from the N.M.R. spectra of N-acetyl compounds prepared from coclaurine and N-norarmepavine.
Interaction of Diclofop-Methyl and MCPA on Wild Oats (Avena fatua)
Diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate} loses part of its activity on wild oats (Avena fatua L.) when it is applied in combination with ester or amine formulations of MCPA {[4-chloro-o-tolyl)oxy] acetic acid.} Uptake of diclofop-methyl is reduced in the presence of commercial formulations of MCPA, particularly amine formulations, which are only partly compatible with the diclofop-methyl formulation. With added MCPA, regardless of formulation, hydrolysis of diclofop-methyl to the acid diclofop is slowed down, both in intact wild oat plants and in a crude leaf extract. At the same time, conversion of any acid formed to inactive conjugates is accelerated in the presence of MCPA. It is concluded that the loss of activity of diclofop-methyl by MCPA can be accounted for by the effects of MCPA on uptake and metabolic conversion of diclofop-methyl.