ABSTRACT
We have revisited the traditional consecutive Michael-Claisen [3 + 3] process (MC-[3 + 3]) promising the synthesis of a cyclohexane-1,3-dione derivatives from nonactivated simple ketones and enoates and evaluated its potential in modern organic synthesis. Twenty to thirty examples were demonstrated to be effective. The reactions exhibited remarkable regioselectivity with the Michael addition proceeding through nucleophilic attack by the more hindered site of the ketones without exception. The subsequent Claisen condensation resulted in the formation of carbon-carbon bonds between less hindered site of the ketones and acyl carbon of the enoates. The MC-[3 + 3] process described is useful for the synthesis of Taxol A-ring synthons in multigram quantities and for the synthesis of other six-membered carbocyclic compounds. A number of control experiments have been conducted to provide strong support for the mechanism of this MC-[3 + 3].
ABSTRACT
A nitrogen analogue 4 of the naturally occurring sulfonium ion salacinol (1), a potent alpha-glucosidase inhibitor isolated from the Ayruvedic medicine Salacia reticulata, was synthesized and its inhibitory activity against alpha-glucosidase tested. Substitution of the sulfur atom in 1 with a nitrogen reduced the activity considerably. The solid-state stereostructure of the related compound (5) was determined on the basis of single crystal X-ray measurement.
Subject(s)
Glycoside Hydrolase Inhibitors , Nitrogen Compounds/chemical synthesis , Sugar Alcohols/chemical synthesis , Sulfates , Animals , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Intestinal Mucosa/drug effects , Intestinal Mucosa/enzymology , Mice , Microvilli/drug effects , Microvilli/enzymology , Nitrogen Compounds/pharmacology , Rats , Sugar Alcohols/pharmacologyABSTRACT
A 68-year-old man with right atrial myxoma detected by abdominal echography accidentally is reported. The diagnosis was confirmed by use of echocardiography and MRI. Selective coronary angiography visualized the tumor vessels. The myxoma was removed successfully. The origin of the tumor was the free wall of the right atrium, and its weight was 14 g.
