Search

Khusinol isolated from vetiver oil was subjected to various chemical modifications. Ester derivatives of khusinol were prepared with acetic anhydride and benzoyl chloride. Epoxides of khusinol were synthesized using perbenzoic acid, vanadium oxyacetylacetonate–t-butyl hydroperoxide, and N-bromosuccinimide– sodium hydroxide. All the compounds showed promising in vitro antifungal potential against Alternaria triticina, Drechslera oryzae, and Fusarium moniliforme with ED50 values in the range of 200–250 μg/mL.

Acyl- and alkyl-derivatives at the N1 and N4 atoms, respectively, of the indoline alkaloids copsinine (1) and pseudocopsinine (2), which were isolated from the plant Vinca erecta, were synthesized. Alkaloids 1 and 2 reacted with alkyl halides to give N4 substitution; with acetic anhydride, N1. In turn, N1-acyl-1 and -2 reacted with alkyl halides to bond the alkyl radical to the N4 position. Reaction products were identified using IR spectroscopy and HPLC-MS. Their structures were elucidated by X-ray crystal structure analyses (XSAs). The tetrahedral hybridization of N1 in the indoline alkaloids was favorable for forming their N1-acetyl derivatives, which is improbable in indole and α-methyleneindoline alkaloids.

A new approach to the synthesis of royal jelly acid (trans-10-hydroxy-2-decenoic acid) was proposed starting from 1,8-octanediol, which included selective monoprotection of 1,8-octanediol with acetic anhydride, oxidation, Wittig-Horner reaction, and hydrolysis and acidification, four steps in total, to yield the product. Overall yield is 80.2%.

N-Acyl cytisine derivatives were synthesized by acylation with acetic anhydride; benzoyl and o-bromo- and p-nitrobenzoyl chlorides; and crotonyl and cinnamoyl chlorides. The structures of the synthesized compounds were studied using IR, PMR, and x-ray structure analysis (XSA). PMR spectra of the N-acylcytisines in solution typically had two rotational isomers around the N12–CO bond. Conformational analysis was performed using XSA for the position of the acyl group relative to the cytisine core. Bond lengths and angles of the acyl groups involved in the conjugation were analyzed.

11-Aminodrim-7-ene was synthesized from drimenol in four steps. Drimenol was oxidized into drimenal and its oxime was dehydrated by p-tosylchloride or acetic anhydride in pyridine to form 9-cyano-11-nordrim-7-ene, reduction of which by LiAlH4 in the presence of anhydrous AlCl3 produced 11-aminodrim-7-ene. The reaction of 9-cyano-11-nordrim-7-ene, NaBH4, and CoCl2·6H2O produced a mixture of drimenylamine and 7,8-dihydrodrimenylamine in a 2:1 ratio.

3-[(E)-Arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolin-1(2H)-ones were prepared by reaction of quinazolyl-2-propionic acid hydrochloride with aromatic aldehydes in acetic anhydride in the presence of Et3N. 3-[(E)-Arylmethylidene]-1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-1-ols were formed by reduction of the 3-arylidene derivatives with sodium borohydride in methanol, readily lost water when heated with acids, and were converted into 3-[(E)-arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolines.

The synthesis from stigmasterol of C-29 brassinosteroids containing an (R)-ethyl group at C24 — (24R)-homocastasterone and (24R)-homobrassinolide — is described. The structure of the carbon skeleton of the side-chain was achieved by condensing a C-22 aldehyde with the appropriate sulfone

From the leaves ofMedicago sativa L. (Leguminosae) we have isolated the glycoside soyasapogenol B — medinoside E. Medinoside E has the structure of olean-12-ene-3β,22β,24-triol 3-O-[O-α-L-rhamnopyranosyl-(1→2)-O-β-D-galactopyranosyl-(1→2)-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranuronoside].

The α- and β-anomers of N1- and N3-monoglycosylated and N1,N3-diglycosylated nucleosides have been synthesized by the condensation of 1-OMe- or 1-O-acetyl-2,3,5-tri-O-benzoyl-D-arabinose with bis(trimethylsilyl)uracil in the presence of SnCl4. The structures of the compounds obtained were established from their NMR spectra.

1-Amino-1,1-bisphosphonates are attracting more and more attention in various areas of chemistry and medicine owing to a combination of unique chemical, physical, and biological properties that enable various biologically active compounds used as immunomodulators, calcium-exchange regulators, antitumor drugs, etc. to be synthesized [1]. Conjugation of natural biologically active compounds and bisphosphonates in order to enhance the binding or accumulation of the biologically active compounds in certain organs in vivo, e.g., bone, is a separate focus area that will, in turn, facilitate targeted delivery of the pharmaceutical. In particular, we reported earlier on modification of folic acid [2]. We decided to synthesize conjugates of bisphosphonic acids with derivatives of betulinic, betulonic, and ursolic acids because they exhibit antimalarial, anticancer, anti-inflammatory, and antiviral activity. Acetylursolic acid was modified by synthesizing its chloride 1 according to the literature method [3]. Then, 1 (0.30 g, 0.6 mmol) was treated with a 10-fold excess of ethylenediamine to give the corresponding amide that was next acylated by acetic anhydride (0.7-mmolar amount) in Py at the free amine group to form the 8a-(2-acetylaminoethylcarbamoyl)4,4,6a,6b,11,12,14b-heptamethyl-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-eicosahydropicen-3-yl ester of acetic acid (2) in 85% yield. Further reaction of 2 (0.35 g, 0.6 mmol) and P(OEt)3 (1.5 mL, 8.8 mmol) in the presence of POCl3 (0.15 mL, 1.6 mmol), analogously to the literature method [4], formed 8a-{2-[1,1-bis-(diethylphosphoryl)ethylamino]ethylcarbamoyl}4,4,6a,6b,11,12,14b-heptamethyl-1,2,3,4,4a,5,6,6a,6b,7,8,8a,9,10,11,12,12a,14,14a,14b-eicosahydropicen-3-yl ester of acetic acid (3) in 70% yield. Apparently, the second amide group was less reactive because of steric hindrance.

A new iridoid — phlomoside B — has been isolated from the epigeal part of the plantPhlomis regelii (M. Pop.). Its structure has been established on the basis of spectral investigations and chemical transformations.

Homologues of pseudobaptigenin containing ethyl and propyl groups in position 2 have been synthesized. The structures of the new compounds have been comfirmed by PMR.

The new diterpene acid salvicinin has been isolated from the epigeal part ofPulicaria salviifolia and its structure has been established as 15-acetoxy-6α-hydroxy-trans-cleroda-3,13-dien-19-oic acid. A capacity of salvicinin for undergoing lactonization in the presence of acetic anhydride has been revealed, and the lactone formed has been isolated and chracterized.

4-H(4-Me)-3-hetarylcoumarins modified by 1,3-benzodioxolane and 1,4-benzodioxane residues have been synthesized. The structures of the compounds obtained have been confirmed by PMR.

The reactions of alkaloids having a 7,8-diol system — lycoctonine, browniine, and dihydromonticoline — with acetic anhydride and p-toluenesulfonic acid have been studied. The optimum conditions for this reaction, leading to anhydro compounds, have been found.

A five-stage synthesis of 8α-acetoxydriman-11-oic acid from the readily available bicyclohomofarnesane-8α,12-diol has been developed.