M. V. Mavrov

Synthesis of N-propargylanabasine derivatives by the mannich reaction

N-Propargylanabasine derivatives bearing various substituents at the carbon atom of the alkyne fragment were obtained by the reaction of anabasine hydrochloride with terminal alkynes and paraformaldehyde. The reaction proceeded with retention of the C(2) chiral center in anabasine fragment. The by-products of the reaction, including 1,3-diacetylene (the products of dimerization of alkynes) and conjugated vinylacetylenes (the rearrangement products of the Mannich adducts) were isolated and characterized.

On the reaction of sterically hindered α,β-unsaturated ketones with hydroxylamine: preparation of 5-hydroxy derivatives of isoxazolidine and 4,5-dihydroisoxazole

A reaction of hydroxylamine with α,β-unsaturated ketones containing a tertiary carbon atom α to the keto group leads to 5-hydroxyisoxazolidine and 5-hydroxy-Δ2-isoxazoline derivatives.

Synthesis of 4-amino-substituted but-2-en-4-olides

Previously unknown 4-amino derivatives of spiro-annelated Δ2-butenolide were synthesized by the addition of various amines at the activated triple bond of 4-hydroxy-2-alkynoic esters.

Synthesis of the grapevine moth sex pheromone by Grignard—Schlosser cross-coupling: The effect of the electrophile structure on the stereoisomeric ratio in the reaction products

Abstract1-Acetoxy-2E,4Z-heptadiene (4) and 1-bromo-3E,5Z-octadiene (5) were obtained with ≥90 and 88–92 % configurational purity, respectively, starting from 2,4-heptadiyn-1-ol or 3,5-octadiyn-1-ol. The Li2CuCl4-catalyzed cross-coupling of the allylic acetate4 with 5tert-butoxypentylmagnesium chloride affords 1-tert-butoxy-7E,9Z-dodecadiene (11) contaminated with ≥25 % of minor stereoisomers in 54–60 % overall yield. Under similar conditions, the homoallylic bromide5 reacts with 4-tert-butoxybutylmagnesium chloride to give in 50–52 % yield another sample of diene11 containing ≤17 % of minor stereoisomers. If the latter coupling is carried out with enyne8 instead of5 followed bycis-hydrogenation of the triple bond in the resulting product, the configurational purity of diene11 is as high as 84.7 % (∼45 % overall yield). The reaction of11 with Ac2O in the presence of FeCl3 leads directly to the target 7E,9Z-dodecadienyl acetate (1) with somewhat lower configurational purity than that of the starting ether11.

Configuration assignment for 3-bromo-2-butenoic acids

Conclusions1H and13C NMR spectroscopy was used for the reliable determination of the configurations of the E- and Z-isomers of 3-bromo-2-butenoic acids and their esters.

Terpenes in organic synthesis. 8. Synthesis of optically active (2R/S, 3S, 7R/S)-(-)-diprionyl acetate from (S)-(+)-3,7-dimethyl-1,6-octadiene

ConclusionsA seven-stage synthesis has given optically active (2R/S, 3S, 7R/S)-2-acetoxy-3,7-dimethylpentadecane from the readily available (S)-(+)-3,7-dimethyl-1,6-octadiene, in an overall yield of 36%. The synthetic route utilizes all ten carbon atoms of the starting chiral diene.

Synthesis of 4-aryl-1,7-dihydroxyalkane-2,6-diones under aldol reaction conditions

Reactions of 3-hydroxyalkan-2-ones with (hetero)aromatic aldehydes under basic conditions lead to 4-aryl-1,7-dihydroxyalkane-2,6-diones. These products were also synthesized by dismutation of 4-aryl-1-hydroxyalk-3-ene-2-ones. The reactions proceed as tandem retro aldol reactions and the Michael addition.

Synthesis of 7E,9Z-dodecadienyl acetate, the sex pheromone ofLobesia botrana Shiff

Two syntheses of 7E,9Z-dodecadienyl acetate from 1,3-butadiyne were carried out using either 2E,4Z-heptadienyl acetate or 1-bromo-3E,5Z-octadiene as the key intermediates. The latter underwent organocopper cross-coupling with the respective complementary Grignard reagents (prepared from the corresponding 1-tert-butoxy-ω-chlorohydrins) as alkylating agents.

Synthesis of (7Z,9Z)-dodecadienyi acetate, a component of sex pheromones of the leafrollersEpinotia andEucosma, using conjugated diynols

Two analogous routes to the title pheromones were elaborated based on organocuprate cross-coupling ofZ,Z-dienic electrophiles, (2Z,4Z)-1-acetoxy-2,4-heptadiene (6) and (3Z,5Z)-1-bromoctadiene (8), with ω-tert-butoxy-1-chloropentane and -butane, respectively. Optimal conditions for the reduction of 2,4-heptadiyn-1-ol and 3,5-octadiyn-1-ol to the respectiveZ,Z-alkadienols as precursors for the electrophiles were found. Treatment of diynols with activated zinc in aqueous alcohol provided high geometrical purity of the product (≥94 %). In both cases, copper-catalyzed cross-coupling afforded 1-tert-butoxy-7,9-dodecadiene (four stereoisomers), acetolysis of which gave the target pheromone contaminated by stereoisomers. In the case of allylic electrophile6, the reaction occurred with the loss of the initial configurational purity, whereas the use of homoallylic bromide8 ensured almost complete retention of the configuration of the double bonds and obtaining the target pheromone of 87 % configurational purity.

A COMPARATIVE STUDY OF THE SYNTHETIC PATHS FROM 1-BUTYNE TO 2E,4Z-HEPTADIEN-1-OL

Abstract2E,4Z-Heptadien-1-ol (1), the key intermediate in the synthesis of the grapevine moth sex pheromone, was obtained from 1-butyne by a number of alternative procedures, including various variants of the stereocontrolled building of the conjugatedE,Z-diene system (Cadiot—Chodkiewicz cross-coupling, alkyne—vinyl halide cross-coupling catalyzed by palladium complexes, anionotropic allylic rearrangement, partialcis- andtrans-reduction of the triple bond). None of them could provide for configurational uniformity of1. The most acceptable path to obtain1 in multigram amounts appears to be that which proceeds via the conjugated diynol and enynol intermediates with subsequent catalyticcis-hydrogenation.