Synthesis of γ-Bicyclohomofarnesal and 14, 15, 16, 20-Tetranorlabdan-8β-13-Diol

The preparation of the ambergris odorant, γ-bicyclohomofarnesal (1) and 14, 15, 16, 20-tetranorlabdan-8β-13-diol (4) from chiral enone 5 is described.     

Synthesis of esters of α-chloroacetoxy-β,β,β,-trichloroethylphosphonic acids

Summary The synthesis of 11 previously unreported dialkyl esters of -mono-, -di-, and -trichloroacetoxy-,,-trichloroethylphosphonic acids has been effected.     

Synthesis of new α,α,β,β-tetrafluoroesters

Substituted phenyl iodides or diiodides reacted with ethyl iodotetrafluoroproponylate ICF₂CF₂CO₂Et, 1 in the presence of copper powder to give the coupled products 2 or 3 in good yields. Addition of 1 to ethylene and allyl acetate proceeded smoothly under thermal and radical conditions to give the corresponding adducts, which underwent elimination reaction to give β-vinyl and β-allyl α,α,β,β-tetrafluoroesters, CH₂CHCF₂CF₂CO₂Et, 4 and CH₂CHCH₂CF₂CF₂CO₂Et, 5, respectively. 1 also readily reacted with 1,5-hexadiene and 1-hexene with copper or palladium complex, followed by reduction to remove iodine to produce ω-alkenyl-α,α,β,β-tetrafluoroester CH₂CH(CH₂)₄CF₂CF₂CO₂Et 6 and α,α,β,β-tetrafluoroester C₄H₉CH₂CHICF₂CF₂CO₂Et.     

Catalytic hydrogenation of substituted 15β-Pregn-16-enes

The catalytic hydrogenation of 15-benzoyloxybutyl-20-hydroxymethylpregn-16-enes under various conditions was studied. It was shown that at the use of a palladium catalyst along with the reduction of the double bond also its shift occurred giving Δ¹⁴-derivatives. The reduction over a platinum catalyst is accompanied by the saturation of aromatic ring of the protecting group, but gives the best yield of the desired products and provides a preparative approach to 15-substituted analogs of brassinosteroids. The structures of the obtained compounds were proved by two-dimensional NMR spectroscopy and HPLC-MS.     

Synthesis of bis-β,β′-spiro-pyrrolidinyl-oxindoles,containing a rhodanine fragment

The synthesis of isatilidene derivatives of N-alkylrhodanines has been carried out with dipolarophiles and unstable azomethine ylides, generated in situ from sarcosine and paraformaldehyde. A series of chiral pyrrolidinyl-oxindoles spirofused in the β,β′-positions has been synthesized in the result of cycloaddition in high yield and diastereoselectivity.     

Synthesis and reactivity of alkenyl- and alkynyl-substituted β,β-dihalo-and β,β,β-trichloroamines

β,β-Dihalo- and β,β,β-trichloroamines, obtained by Lewis acid-promoted Petasis-type reaction of α,α-dichlorinated and α,α,α-trichlorinated imines or reduction of α,α-dihaloaldimines, were subjected to a reactivity study and turned out to be remarkably stable compounds. In general, only the bases KO^tBu and NaOMe cause a 1,2-dehydrochlorination with formation of unsaturated α-chloroimines or unsaturated α,α-dichloroimines. Hydrolysis of the α-chloroimines with aqueous oxalic acid resulted in the formation of the corresponding unsaturated α-chloroketones. The reaction of simple β,β-dihaloamines with NaOMe and KO^tBu generated 2-haloprop-2-enylmines and 2,2-dimethoxypropylamines.     

Synthesis of α,β-Unsaturated Ketones via Enamines

Acylation of an enamine followed by acid hydrolysis constitutes the well-known Stork's reaction of synthesizing β-diketones.^1,2 This article reports that the acylated enamine 1 which corresponds to monoenamine of a β-diketone can be hydrogenated to a Mannich base 2 which on elimination by heating or treatment with acid yields the α, β-unsaturated ketone 3; further hydrogenation gives saturated ketone 4 in good yield (Scheme 1). A similar transformation effected by hydroboration has been reported by Montury and Góre.     

Synthesis of Deoxytabtoxinine-β-Lactam

Deoxytabtoxinine-β-lactam (12) was synthesized in 6 steps from 3. β-Lactam 12 does not inhibit glutamine synthetase indicating that the hydroxyl group of tabtoxinine-β-lactam (2) is necessary for inhibition of glutamine synthetase.     

Synthesis of α,α-dideutero-β-amino esters

A straight forward entry to α,α-dideutero-β-amino esters starting from the corresponding imines and deuterated acetonitrile has been developed involving a two-step process.     

A Convenient Synthesis of α,β-unsaturated Nitriles

α,β-unsaturated nitriles were synthesized by the reaction of aldehydes with bromoacetonitrile promoted by tri-n-butylphosphine and zinc.     

Crystal Structure of 6β,7β,14β-Trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one

6β,7β,14β-Trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one was isolated from the natural plant of Isodon japonica (Burm.f), Haravar. galaucocalyx (maxim) Hara. The structure was elucidated by means of spectral and chemical studies. In addition, its crystal was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P1, Z = 2, a = 6.3506(4), b = 13.5766(8), c = 15.2777(9) , α = 80.506(1), β = 83.856(1), γ = 88.307(1)o, C25H36O9, Mr = 480.54, V = 1291.64(13) 3, Z = 2, Dc = 1.236 g/cm3, F(000) = 516, μ = 0.093 mm-1, S = 0.988, the final R = 0.0761 and wR = 0.1955. Flack factor is 0.02(19), and the largest peak and deepest hole on the final difference Fourier map are 0.556 and –0.265 e/3, respectively. The X-ray diffraction shows the existence of intermolecular C–H…O (DA) hydrogen bonds between adjacent molecules.     

Synthesis of β,β‘-Difluorinated and β,β’-F-Dialkylated Acetals

Using the phase transfer catalysis technique, a series of fluorinated acetals has been prepared, in basic medium, by action of dicholromethane on 2-mononfluorinated alcohols or 1-F-alkyl 2-fluoroethanols. The identification of these new acetals has been achived by the study cf their ¹H, 19F NMR and their mass spectra.     

Novel Synthesis of 2β,3β,20β-Triacetoxy-5 -pregnan-6-one

Pregnenolone (2) is used in a novel synthesis of 2,3,20-triacetoxy-6-ketosteroid (6), a key intermediate in the preparation of 20-hydroxyecdysone (1)     

Synthesis of β-Fluoroalkyl-β,β-dimethoxy Ketones and β-Fluoroalkyl-β-methoxy-α,β-enones

α-Bromo-β-fluoroalkyl-α,β-enones react with sodium methoxide in methanol to give the corresponding β-fluoroalkyl-β,β-dimethoxy ketones which eliminate methanol molecule to produce a mixture of E/Z-isomeric β-fluoroalkyl-β-methoxyvinyl ketones, the Z isomer prevailing.     

Synthesis of 5α, 13α, 14α-Androstan-16-One and 5α, 13β, 14β—Androstan-16-One Using a Novel 17–16 Carbonyl Transposition

In the course of current work on the conformational analysis of cis-hydrindanones¹, we required 5α, 13α, 14α and 5α, 13β, 14β-androstan-16-one 5 and 10 the C and D rings of which provide rigid models of the two conformations of cis-hydrindan-2-one.     

Synthesis ofN-chioroacetyl-β-glycopyranosylamines,derivatives of monosaccharides and lactose

N-Chloroacetyl--glycopyranosylimines were synthesized from various monosaccharide (hexoses, pentoses, deoxysugars, uronic acids, and sugar phosphates) and a disaccharide (lactose) byN-acylation of the corresponding -glycosylamines with chloroacetic anhydride in DMF In some cases, treatment of rnonosacc harides with NH₃ in the presence of (NH₄)₂CO₃ in MeOH or aqueous MeOH was more efficient than the methods previously described, as it gave -glycosylarnines in higher yields.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1848–1851, July, 1996.