Vol 59, No 6 (2023)

The review describes the low-temperature reduction of (-)-mentholactone with diisobutylaluminum hydride in methylene chloride studied by the authors. It was found that, depending on the reaction conditions, it proceeds with the formation of three products: 7 S -isopropyl-4 R -methyloxepan-2 S -ol [(-)-mentholactol], 8-hydroxy-2,6 R -dimethyloctan-3-one or 2 S -isobutoxy-7 S -isopropyl-4 R -methyloxepane, for each of which the probable routes are given and the conditions for selective formation are selected. A new reaction in the chemistry of organoaluminum compounds has been discovered - the formation of isobutyl acetals of 2-oxepanols during low-temperature (-70°C) reduction of 7-membered lactones with two-fold or more molar amounts of diisobutylaluminum hydride in methylene chloride. On the basis of (-)-mentholactol, its aluminate, and 8-hydroxy-2,6R-dimethyloctan-3-one, a number of low molecular weight bioregulators, including optically active pheromones of insect pests in agriculture and forestry, have been synthesized.

The hydrogenation of 16-nitro-14,17-ethenosteroids over various catalysts was studied, chemoselectivity criteria have been established, new bridged estradiol analogs bearing nitro, amino and hydroxylamino groups in the D ring have been prepared. A complete assignment of signals in the NMR spectra of the synthesized products was fulfilled

Condensation of 4,4-dichlorobut-3-en-2-one with aromatic aldehydes in the presence of catalytic amounts of sulfuric acid leads to the formation of 1,1-dichloro-5-(4-R-phenyl)penta-1,4-diene-3-ones. The reaction of 1,4-dien-3-ones with hydrazines proceeds chemo- and regioselectively under mild conditions with the formation of ( E )-1-methyl-3-styryl-5-chloro-1 H -pyrazoles with a yield reaching 81%. 4-Bromo-1,1-dichloro-5-(4-methoxyphenyl)penta-1,4-dien-3-one reacts with dimethylhydrazine to give 3-[1-bromo-2-(4-methoxyphenyl)vinyl]-5chloro-1-methyl-1 H -pyrazole, which in the presence of KF in DMSO at 120°C forms 1-methyl-3-[(4-methoxyphenyl)ethynyl]-5-chloro-1 H -pyrazole with 69% yield. The structure of the synthesized compounds has been confirmed using IR, NMR spectroscopies, mass spectrometry, and elemental analysis.

Reaction of silver-¹³C carbonate, obtained from readily available barium-¹³C carbonate, with 1-iodobutane resulted in formation of di( n -butyl)carbonate-( carbonyl -¹³C) isolated in high yield via simple and convenient laboratory procedure.

An efficient method for the synthesis of di(6,7,13,14,18,19-hexaoxa-16-azadispiro[4.2.4⁸.7⁵]nonadecan-16-yl)methane(thi)ones and N -substituted hexaoxaazadispiroalkanecarboxamides by the reaction of 3,6-di(spiroalkane)substituted heptaoxacycloundecanes with thiourea and urea derivatives (urea, 1,1-dimethylurea, 1-phenylurea, 1-allylurea) with the participation of Sm(NO₃)₃·6H₂O as a catalyst.

Enantioselective aminomethylation of 1-(benzyloxy)propan-2-one with an aromatic propargyl amino ether in the presence of a chiral pseudoephedrine catalyst in an aqueous medium gave anti / syn products with high yields and optical purity.

By 1,3-dipolar cycloaddition to nitrile N -oxide obtained from 6-methyluracyl-5-carboxymidoyl chloride, compounds containing an allyl component or propargyl alcohol, a number of 2-isoxazolines and isoxazole with uracil fragments were synthesized.