Shikimic acids from furan; methods of stereocontrolled access to 3,4,5-trioxygenated cyclohexenes

Oxabicycloheptenes 1 and 2 are converted to 3,4,5-oxygenated cyclohexenes by stereocontrolled hydroxylations and epoxidations coupled with reverse-Michael cleavage of the oxabicyclo system. Three epimers of shikimic acid are synthesized by these methods.

Radionuclide venographic demonstration of portal and systemic collaterals in a case of complete IVC obstruction

Radionuclide venography can be used to assess deep venous thrombosis and IVC obstruction. We present a case which, to our knowledge, has not been previously described, in which the entire liver and lungs are simultaneously visualized secondary to portal-caval and caval-systemic collaterals, respectively.

An exceptional 5-endo–trig reversal; a convergent synthesis of daunomycinone

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An exceptional 5-endo–trig reversal; a convergent synthesis of daunomycinone

A convergent AB + CD route to daunomycinone (1) is described. The AB segment is synthesized from the Diels–Alder adduct (3) of an isobenzofuran and methyl vinyl ketone by means of an unusual 5-endo–trig cleavage (3 → 4). The CD half (9) is combined with the AB by the Kraus annelation technique to provide a 9-deoxy daunomycinone derivative (12a) which is subsequently oxygenated.

Effects of chemical transmitters on function of isolated canine parietal cells

In view of the complexity of the regulation of gastric acid secretion, isolated parietal cells offer the appealing prospect of studying the receptors and mechanisms activating this cell after it has been removed from the confusing milieu of the intact mucosa. Histamine and cholinergic agents stimulate the function of canine parietal cells by interacting with typical H2 and muscarinic receptors. Gastrin produces only a small stimulation, interacting with a third, presumably specific, receptor. Combinations of histamine and carbachol and of histamine and gastrin produce potentiating interactions. When isolated parietal cells are treated with these combinations of agents, cimetidine and atropine display and apparent lack of specificity, reminiscent of that found in vivo, and probably resulting from interference with the histamine and cholinergic components of these potentiating interactions. The action of histamine, but not of carbachol or gastrin, is linked to stimulation of cyclic AMP production by parietal cells. Two potential inhibitors of acid secretion, secretin and prostaglandin E2, also stimulate cyclic AMP production, but these later effects appeared to occur largely in nonparietal cells. PGE2 however specifically inhibits histamine-stimulated parietal cell function, apparently by blocking activation of adenylate cyclase. Cholinergic action on the other hand is closely linked to enhanced influx of extracellular calcium.

A versatile synthesis of spirobenzylisoquinoline and phthalideisoquinoline alkaloids. Conversion of a phthalideisoquinoline to spirobenzylisoquinolines

Eight spirobenzylisoquinolines and four phthalideisoquinolines have been synthesized through 1,9-dehydrophthalideisoquinoline intermediates. The latter are reduced and rearranged in one step to spirobenzylisoquinolines of the corydaine–sibiricine type. The phthalideisoquinoline alkaloid hydrastine has been converted by invitro methods to a spirobenzylisoquinoline in two steps.

[Metabolic regulation of nutrition]

The mechanisms regulating nutrient metabolism and their adaptation and compensation during stress conditions are discussed. The stress conditions considered are fasting and refeeding, pregnancy, growth and development, and malnutrition.

Chemistry of the Podocarpaceae. LIV. Lignans from the Wood of Dacrydium intermedium

Structures and absolute configurations are established for three new lignans isolated from the wood of the New Zealand gymnosperm Dacrydium intermedium Kirk by preparative h.p.l.c. of their acetates (1), (3) and (5). The 1H and 13C N.M.R. spectra of phenyltetralin lactones and acetals are described.

Cancentrine. IV. Acetolysis Products of Cancentrine Methiodide

Treatment of cancentrine methiodide with boiling acetic anhydride in the presence of sodium acetate gave two highly unsaturated products formed in rearrangement reactions. One of the products retained all the original carbon and both nitrogen atoms of cancentrine while the other formed with loss of three carbon atoms and one nitrogen atom. The structures of the two compounds were deduced through analysis of their p.m.r. spectra and through comparison of their p.m.r. and u.v. spectra with those of model compounds synthesized in this study. A mechanism for the formation of the rearrangement products is proposed and discussed.

The Triterpenes of Lycopodiumlucidulum Michx

Nine known serratane triterpenoids have been isolated from Lycopodiumlucidulum Michx. mostly as their acetates. Serratenediol is the major one and is accompanied by significant amounts of serratriol. Moderate quantities of serratenediol-3-acetate, tohogenol, and episerratenediol were present together with minor amounts of 16-oxoserratriol, tohogeninol, and the phlegmanols A and E.

The Total Synthesis of (±) Ochrobirine

The total synthesis of (±) ochrobirine is described.

An Unusual Oppenauer Oxidation of (±) Ophiocarpine

The Oppenauer oxidation of (±) ophiocarpine has been carried out to yield 3-(2′-vinyl-3′,4′-methylenedioxy) phenyl-4-hydroxyisoquinoline (2). Photolysis of this compound gave 3,4-dimethoxy-11,12-methylenedioxy-8,9-dihydro[1]benzoxepino(2,3-c) isoquinoline (7), whereas photolysis of the methyl ether of 2 produced N-norchelerythrine.

Cancentrine. III. Dehydroderivatives

The structures of dehydrocancentrine-A and -B are elucidated by a combination of physical and chemical methods.

Cancentrine. II. The Structure of Cancentrine

The structure of cancentrine (F22), an alkaloid of Dicentracanadensis (Goldie) Walp., is reported. Some reactions of the base are described and an analysis of the p.m.r. and mass spectra of cancentrine and several derivatives is made.

Structure of sibiricine, an alkaloid of Corydalissibirica

Structure 1 is proposed for sibiricine, a minor alkaloid of C. sibirica. The structural assignment rests on an interpretation of its mass spectrum and its proton magnetic resonance (p.m.r.) spectrum.

Some benzophenanthridine alkaloids from Bocconiaarborea

The minor alkaloids of B. arborea have been identified. Three of them have been shown to be dihydro-sanguinarine, oxysanguinarine, and 11-O-methyldihydrochelerythrine respectively. The structure of the fourth has been established by physical methods and by synthesis as the hitherto unknown 1,3-bis(11-hydrochelerythrinyl)acetone. It does not appear to be an artefact. The high resolution mass spectra of some dihydrochelerythrine derivatives are discussed.