Molecular requirements of the recognition site of cholinergic receptors. 22. Resolution, absolute configuration, and cholinergic enantioselectivity of (+)- and (-)-cis-2-methyl-5-[(dimethylamino)methyl]-1,3-oxathiolane methiodide
The potent cholinergic agonist (+/-)-cis-2-methyl-5-[(dimethylamino)methyl]-1,3-oxathiolane methiodide (+/-)-1] was resolved into enantiomeric forms. Their absolute configurations were established by a synthetic pathway that also allowed the synthesis of the corresponding diastereomeric (+)- and (-)-trans-2-methyl-5-[(dimethylamino)-methyl]-1,3-oxathiolane methiodide [(+)- and (-)-10]. Compound (+)-1, which is the most potent of the four isomers, showed the same absolute configuration as L-(+)-muscarine and (+)-cis-dioxolane. The four isomers were tested on guinea pig ileum and frog rectus abdominis, and their muscarinic and nicotinic potency (EPMR) and selectivity were determined. The relationships between stereoisomerism and potency are discussed.
Molecular requirements of the recognition site of cholinergic receptors. 27. Enantioselectivity of muscarinic antagonists. 2,2-Dicyclohexyl-5-[(dimethylamino)methyl]-1,3-oxathiolane methiodides and related 3-oxides
The enantiomers of three chiral muscarinic antagonists carrying a 1,3-oxathiolane nucleus were prepared and their absolute configuration established. The enantioselectivity and tissue selectivity of such compounds were studied on rat bladder and guinea pig ileum and heart. The results show that introduction of a sulfoxide function brings about a small but definite enantioselectivity in the 1,3-oxathiolane compound (2), which in itself does not show enantioselectivity among the tissues studied. The results obtained point to differences among cardiac and ileal muscarinic receptors. Comparison of the absolute configuration related agonists shows that the most potent isomers of both series share the same absolute stereochemistry.
TEODORI E.; GUALTIERI F.; ANGELI P.; BRASILI L.; GIANNELLA M.; PIGINI M., J. MED. CHEM., 29,(1986) N 9, 1610-1615
The first total synthesis of the recently isolated natural product thiocladospolide A, along with its C2-epimer, is achieved in nine straightforward linear steps and 12% overall yield. The key feature of the synthesis is the construction of the macrocyclic ring via a late-stage ring-closing metathesisreaction followed by alkene reduction.
最近分离的天然产物 thiocladospolide A 及其 C2-差向异构体的首次全合成是通过 9 个简单的线性步骤实现的,总产率为 12%。该合成的关键特征是通过后期闭环复分解反应构建大环,然后进行烯烃还原。