A Facile Syntheses of 6-Bicyclo[3.2.1]octanones

Copper oxide-catalyzed decomposition of 1-diazoacetyl-1-methyl-3-methylenecyclohexanes produces strained tricycles whose reduction or hydrolysis affords 6-bicyclo[3.2.1]octanones.     

Asymmetric Syntheses Based on Hexahydro-4,4,7-Trimethyl-1,3-Benzoxathians

Abstract

Earlier work concerned with a highly stereoselective asymmetric synthesis based on a 1,3-oxathiane as the ciral auxiliary reagent is reviewed and recent applications to the synthesis of the four stereoisomers of malyngolide, of (R)-(+)-γ-caprolactone (a pheromone of the Trogoderma glabrum beetle) and of (S)-(+)-mevalolactone are presented. The mechanism underlying this asymmetric synthesis is discussed briefly.     

Kinetic Study on Models of the Noncatalyzed Reaction Between α, ω -Dicarboxypolyamide-11 and α, ω -Dihydroxypolyoxyalkylenes

The kinetics of the noncatalyzed reaction between α, ω -dicarboxypoly-amide-11 and α, ω -dihydroxypolyoxyalkylenes is investigated by using the reactions of 11-dodecylamidoundecanoic acid with 1-dodecanol, 2-tridecanol, α-dodecyl-ω-hydroxypolyoxyethylene or α-dodecyl-ω;-hydroxypolyoxypropylene as models. Kinetic data fit a 3rd overall order (2 in acid and 1 in alcohol). Rate constants and activation parameters are determined and compared.     

Acid-Catalyzed Diels-Alder Reactions of Cycloalkenones

Whereas the Diels-Alder reaction has been in vogue as a facile method of six-membered ring construction for many years, its application to a one-step cis-octalone synthesis was precluded by discouraging, early reports on the conditions required for the interaction of dienes with 2-cyclohexenones and on the yields of the resultant adducts.^1,2 It is quite conceivable that these observations were responsible in part for the minimization of use of an otherwise attractive route toward angularly alkylated six-membered polycycles in the field of steroid total synthesis. The discovery of Lewis acid catalysis of the cycloaddition of α, β-unsaturated carbonyl compounds³ has rekindled interest in the above reactions.⁴ The following discussion illustrates octalone     

20-ISO-20-Deethylaspidospermidine

The two-step process of hydrogenation of l-alkyl-3-acylpyridinium salts and cyclization of the resultant 1, 4, 5, 6-tetrahydropyridines has been the foundation of a general scheme of alkaloid synthesis.¹ Its application in the indole alkaloid field has yielded ready access to tetrahydro-β-carboline systems, e.g. 1a → 2 → eburnamonine.² Since acid treatment of N_b -acyl derivatives of substances related to la has been shown to lead to products of indole β-cyclization³, it became of interest to test the cyclization behavior of the vinylogous imide lb, prepared by the dicyclohexylcarbodiimide-induced acylation of 3-acetyl-1, 4, 5, 6-tetrahydropyridine⁴ with indoleacetic acid. Treatment of lb with boron trifluoride gave a 62 yield of ketolactam 3a. Thus a two-step entry into the pentacyclic Aspidosperma alkaloid skeleton is on hand.