A. G. Tolstikov

SULFUR-CONTAINING DERIVATIVES OF MONO- AND BICYCLIC NATURAL MONOTERPENOIDS

Examples of thiylation of natural mono- and bicyclic and variously functionalized monoterpenoids (alkenes, ketones, epoxides, alcohols) and the latest transformation pathways of the newly formed sulfur-containing derivatives were reviewed.

Synthesis of macrolides containing an azine or hydrazide fragment via successive tishchenko disproportionation and [1 + 1]-condensation

Eight potentially useful 15-, 17-, 20-, and 22–25-membered macrolides having an azine or hydrazide fragment were synthesized starting from L-menthol, tetrahydropyran, and 4-methyltetrahydropyran via [1 + 1]-condensation of hydrazine hydrate and some dicarboxylic dihydrazides with 7-oxooctyl 7-oxooctanoate, 3-methyl-7-oxooctyl 3-methyl-7-oxooctanoate, and (3R)-3,7-dimethyl-6-oxooctyl (3R)-3,7-dimethyl-6-oxooctanoate obtained by the Tishchenko reaction from 7-oxo-, 3-methyl-7-oxo, and (3R)-3,7-dimethyl-6-oxooctanals, respectively.

Synthesis of optically active macrolides with hydrazide fragments from tetrahydropyran and L-(+)-tartaric acid derivatives

The synthesis of two potentially useful optically active 23- and 30-membered macrolides containing a 1,2-diol system and dihydrazide fragments was developed starting from tetrahydropyran. It was based on [1+1]-condensation of 7-oxooctyl-7-oxooctanoate and bis(7-oxooctyl)hexanedioate with L-(+)-tartaric acid hydrazide.

Synthesis of macrocyclic azino and dihydrazido diesters by consecutive [2 + 1]- and [1 + 1]-condensations

Efficient procedures for the synthesis of 21–24- and 28–31-membered macrocyclic azino diesters and dihydrazido diesters were developed starting from L-menthol, Δ3-carene, (+)-α-pinene, tetrahydropyran, and 4-methyltetrahydropyran. The key steps in these syntheses were consecutive [2 + 1]- and [1 + 1]-condensations. The 31-membered dihydrazido diester exhibited strong antibacterial activity.

Synthesis of macrolides with N-containing (azine or hydrazide) groups

Potentially useful 17-, and 22÷25-membered macrolides containing azine or hydrazide groups were synthesized from tetrahydropyran via [1+1]-condensation at room temperature of 7-oxooctyl-7-oxooctanoate, which was obtained via Tishchenko reaction from 7-oxooctanal, with hydrazine hydrate and hydrazides of several dicarboxylic acids.

Synthesis from (–)-α-Pinene of an Optically Active Macrocyclic Diesterdihydrazide with 2,6-Pyridinedicarboxylic and Adipic Acid Moities

An optically active macrocyclic diesterdihydrazide with 2,6-pyridinedicarboxylic and adipic acid moieties was synthesized efficiently from available (–)-α-pinene through an intermediate hydroxyketone [1R-(1′-hydroxyethyl)-3R-(2″-hydroxyethyl)-2,2-dimethylcyclobutane) using successive [2 + 1]-reaction of the last with 2,6-pyridinedicarboxylic acid dichloride and [1 + 1]-condensation of the resulting diketodiester with adipic acid dihydrazide.

Synthesis of C2 symmetric triterpene bis-enaminones

Mono- and dicondensed triterpene enaminones were prepared by reaction of oleanane- and lupane-type 2hydroxymethylene derivatives with aliphatic and aromatic diamines in the presence of catalytic amounts of HOAc.

NATURAL SEVEN-MEMBERED TERPENE LACTONES: SYNTHESIS AND BIOLOGICAL ACTIVITY

Until now, about 400 different natural seven-membered terpenoid lactones have been isolated from a broad spectrum of organisms. The majority (245) of the reported compounds occurred in plants. A significant number (101) of the sevenmembered lactones were isolated from marine organisms. The fewest (22) were secondary metabolites of microorganisms. Thus, oxepanones are confirmed to be widely distributed natural compounds that play various biological roles in diverse living organisms. Research on the biological activities of the principal isolated 2-oxepanones showed that most of them exhibit antimicrobial, antifeedant, insecticidal, antioxidant, anti-inflammatory, and anticancer properties. Several of them are used in agriculture as plant growth inhibitors. For example, limonoids isolated from Harrisonia abyssinica suppressed sprouting of seeds of the pathogenic plant Striga, which parasitizes the root system of crops and reduces the yields of grains and beans [1]. Derivatives of natural seven-membered lactones are also used in pharmacology. Thus, the limonoid prieurianin, which was isolated from Entandrophragma candolei (Meliaceae), could be used to prevent obesity even in diabetes patients [2]. Chiisanogenin obtained from the alcohol extract of Acanthopanax (Eleutherococcus) senticosus is a biologically active constituent that treats diseases associated with glycation [3]. Despite definite success, information on the biological properties of natural seven-membered terpene lactones is still limited. Further research could embellish the understanding of their mechanisms of biogenesis and their biological roles in nature and medicine. The goal of the present review was to organize information on seven-membered terpene lactones with respect to their structures, occurrence in nature, synthetic accessibility, and pharmacological activity. 1. Natural seven-membered terpene lactones: structures, occurrence in nature, and biological activity

Low-Temperature Reduction by Diisobutylaluminum Hydride in CH2Cl2 of Seven-Membered Lactones from Betulin and S-(+)-Camphor

The behavior of seven-membered lactones from the triterpenoid betulin and S-(+)-camphor in a novel reaction with organoaluminum compounds was studied using low-temperature reduction of monoterpene sevenmembered lactones by an excess of diisobutylaluminum hydride in CH2Cl2.

Ozonides with the tetrahydroquinoline and dehydroabietic fragments

Acid-catalyzed three-component condensation of methyl 12-aminodehydroabietate, aromatic aldehydes, and cyclopentadiene gave methyl (4R)-4-aryl-6-isopropyl-10,13a-dimethyl-3a,4,5,8,9,9a,10,11,12,13,13a,13d-dodecahydro-3H-cyclopenta[c]naphtho[1,2-f]quinoline-10-carboxylates and their (4S)-diastereomers. Ozonolysis of the double bond in their N-trifluoroacetyl derivatives synthesized from the (4R)-diastereomers afforded the corresponding ozonides with the (1S,4R,5aS,6R,11aR,12R,15aS,15dR)-configuration.