A highly efficient iridium-catalyzed asymmetric hydrogenation of tetrasubstituted cyclicenones has been developed for the enantioselective synthesis of chiral cycloalkanols with three contiguous stereocenters. The C═O and C═C bonds of the enone substrates were hydrogenated sequentially in one pot with excellent enantioselectivity (92 to >99% ee) and diastereoselectivity (dr 95:5 to >99:1). The reaction
Diethyl 3, 6-dioxooctanedioate (5), which can be prepared readily from ethyl acetoacetate and ethyl γ-bromoacetoacetate, was utilized for a facile preparation of dl-dehydroiridodiol (1). Compound 5 was treated with sodium hydroxide to give ethyl 2-ethoxycarbonyl-3-oxo-1-cyclopenteneacetate (6), which was methylated, and then reduced to give ethyl 2-(2-ethoxycarbonyl-3-oxocyclopentyl) propionate (8). Compound 8 was transformed to the phosphate (9). On methylation with lithium dimethylcuprate, followed by reduction, the phosphate (9) was converted to dl-dehydroiridodiol (1) via ethyl 2-(2-ethoxycarbonyl-3-methyl-2-cyclopentenyl) propionate (10).
Willstaetter; Pfannenstiel, Justus Liebigs Annalen der Chemie, 1921, vol. 422, p. 11
作者:Willstaetter、Pfannenstiel
DOI:——
日期:——
Synthesis of Hexahydro-2-pyrindine (=Hexahydrocyclopenta[c]pyridine) Derivatives as Conformationally Restricted Analogs of the Nicotinic Ligands Arecolone and Isoarecolone
Two hexahydropyrindine derivatives. 1,2,3,4,6,7-hexahydro-2-methyl-5H-cyclopenta[c]pyridin-5-one (1) and 1.2.3.4.5.6- hexahydro-2-methyl-7H-cyclopenta[c]pyridin-7-one (2), and their methiodides 14 and 26, respectively, were synthesized. They can be considered rigid analogues of the known nicotinic agonists arecolone (=1-( 1,2,5 6- tetrahydro-l-methylpyridin-3-yl)ethanone) and isoarecolone(= 1-( 1,2,3,6-tetrahydro-1-methylpridin-4-yl)ethanone). The affinity for the central nicotinic receptor were measured on rat cerebral cortex. Although only the methiodide 14. among the four conformationally restricted compounds, shows an appreciable affinity. the results obtained provide useful information on the molecular requirements at the interaction site of the central nicotinic receptors.
Willstaetter; Bommer, Justus Liebigs Annalen der Chemie, 1921, vol. 422, p. 30