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N-Sulfinylanilines derived from 4-bromoaniline, 3-nitroaniline, and 4,4′-di(ethane-1,2-diyl)dianiline were synthesized. X-ray diffraction analysis of 4-bromo-N-sulfinylaniline, 3-nitro-N-sulfinylaniline, and 4,4′-(ethane-1,2-diyl)di-N-sulfinylaniline was performed. The sulfinyl function in the planar conformation of the Ar-NSO fragment was found to have Z configuration. The nature of intra- and intermolecular structure-forming interactions was established.

Current developments in the pharmaceutical industry indicate an increase in attention towards natural products and their analogues. This is primarily due to the availability and variety of natural organic structures that exhibit a wide range of biological activity. Unique among them is the several individual classes of natural products of mixed biogenic origin with isoprenyl fragments. These conjugated biosynthetic compounds are formed from isoprenyl fragments and fragments of other classes of natural metabolites (flavonoids, alkaloids, lipids, peptides, etc.) synthesized by other pathways. They are combined into one common group called meroterpenoids. Interest in meroterpenoids is due to their unique hybrid structure, where the terpene is either the main unit or is part of the compound as a functional group. Thus, they have diverse practical applications. For example, the biological properties of isoprenyl flavonoids are primarily associated with the properties of phenolic compounds, which are characterized by their antioxidant activity. Introduction of isoprenyl substituents, therefore, plays a modifying role, resulting in an increase in their lipophilicity and variation in their oxidation-reduction potential. Substances with antitumor activity, HIV-1 transcriptase inhibitors, immunomodulators, and antifeedants have been identified among meroterpenoids containing the quinone fragment. The presence of alkaloid and saponin meroterpenoids explains the medicinal properties of a number of plants used in medicinal chemistry around the world. The review considers progress in the synthesis and functionalization of isoprenoids in conjugate biosynthesis. A detailed classification of meroterpenoids is made in accordance with the role of the isoprenoid fragment and the class of compounds to which this fragment belongs. The schemes and mechanisms of conjugated biosynthesis are discussed. Particular attention is paid to the phenol-flavonoid derivatives, isoprenoid lipids, terpenic alkaloids and isoprenyl glycosides. Also, structure-property patterns are considered. In addition, issues related to the biological activity of various classes of meroterpenoids, which have found application in the therapy of cardiovascular diseases, diabetes, inflammatory processes, tumors, tropical diseases, etc., are discussed in detail.

1,2,3,4,4a,10b-Hexahydro-1,4-methano-6H-dibenzo[c,e]-5,6-thiazine-5,5-dioxide has been converted into the corresponding N-acyl derivatives via the reaction with acid chlorides and anhydrides. X-Ray diffraction data have revealed the presence of an intramolecular С–H···O=S hydrogen bond in the molecules of the obtained compounds.

N-Sulfinyl-3-(trifluoromethyl)aniline reacted with bicyclo[2.2.1]hept-2-ene and bicyclo[2.2.1]-hepta-2,5-diene to give the corresponding Diels‒Alder adducts which were oxidized to 8-trifluoromethyl-2,3,4,4a,6,10b-hexahydro-5λ6-1,4-methanodibenzo[c,e][1,2]thiazine-5,5(1H)-diones. The cycloaddition occurred predominantly with participation of the S=N–C1=C6 fragment of N-sulfinyl-3-(trifluoromethyl)aniline and exclusively at the endo side of bicyclo[2.2.1]heptenes.

An X-ray crystallographic study of a new compound is performed and the structure of five sulfin- and sulfonamides of the thiazine series is discussed. The conformation of the thiazine ring in all structures (a distorted boat) is stabilized by the intramolecular interaction of the C-H…N type. The nitrogen atom of the thiazine ring has a pyramidal configuration. The geometry of isolated molecules is calculated at density functional theory level (PBE1PBE, 6-31G(d,p)) and compared to that observed in the crystals. In the crystal structures different packing motifs are implemented with the formation of supramolecular associates of different types due to classical hydrogen bonds such as N-H…O.

New water-soluble decasubstituted pillar[5]arenes containing glycine and glycylglycine fragments were synthesized and characterized. The UV, DLS and TEM study showed that interaction of self-associates of the glycylglycine derivatives with Bismarck brown Y produced particles of about 59 nm in size.

An X-ray structural examination is carried out for 2,3-dimethyl-5-(2′-methylprop-1′-enyl)-6-(morpholyl-4′-carbonyl)-cyclohex-3-en-1-carboxlic acid that is one of the products of the Diels-Alder reaction of an acyclic monoterpene alloocimene with maleic and citraconic anhydrides followed by the ring opening of adducts with morpholine to corresponding amides. The crystals are triclinic; a = 10.619(1) A, b = 12.784(2) A, c = 14.328(2) A; α = 65.752(1)°, β = 87.932(1)°, γ = 78.120(1)°; V = 1733.0(3) A3, P-1 space group, Z = 4 (two independent molecules). In both molecules, the anti-conformation of the carboxylic group is observed, the conformation being stabilized by an intramolecular hydrogen bond involving the carboxylic hydrogen atom and ketonic oxygen.

Reactions of alloocimene with maleic and citraconic anhydrides gave the corresponding Diels-Alder cycloaddition products which may be regarded as new synthetic sesquiterpenoids. The molecular structures of the adducts, determined by X-ray analysis, indicated endo addition of the dienophiles at the most sterically accessible diene system and syn-boat conformation of the bicyclic skeleton.

The reactions of 1-methylcycloprop-2-ene-1-carbonitrile with cyclohexa-1,4-diene and alloocimene gave the corresponding 2:1 addition products as a result of consecutive (conjugate) Alder-ene and Diels-Alder reactions. 1-Methylcycloprop-2-ene-1-carbonitrile acts initially as enophile, and in the second step, as dieno- phile. The structure of the adducts was determined by X-ray analysis.

At elevated temperatures 3-methyl-cyclopropene-3-carbonitrile 1 was found to tetramerize giving compound 2 (3-methyl-2,3-bis(2-t-methyl-2-c-cyanocyclopropyl)-1-(2-t-methyl-2-c,3-c-dicyanocyclopropyl)-cyclopropene) in good yields. This is the first example of Alder-ene type oligomerization of a 3,3-disubstituted cyclopropene. On the basis of the product geometry and stereoselective character of the reaction, a mechanism of formation of 2 involving CN-Alder-ene reaction was proposed. DFT modeling of the mechanism has shown that the CN-Alder-ene reaction is possible as a stepwise process involving a biradical intermediate.

7,7-Dimethyl-2,10-epoxybicyclo[3.1.1]heptane obtained by treatment of (-)-β-pinene with peroxybenzimidic acid has α configuration.

The stereochemistry of elimination in chlorocyclopropane was investigated using ab initio (6-31(+)G∗//HF/6-31(+)G∗) calculations. The competitive SN2 route was also considered. Transition states were located for the E2(anti), E2(syn) and SN2 reactions. The three-membered ring has a pronounced effect on the syn/anti preference of E2 elimination; the barrier of syn elimination (22.2 kcal mol−1) is only 3.6 kcal mol−1 larger than that of anti elimination. The small syn/anti difference is related to the inherent periplanarity of the syn transition state and the torsional ring strain of the anti transition state. Comparing the reaction of F− with cyclopropyl, cyclopentyl and cyclohexyl chlorides, it was found that the tendency for anti elimination is especially reduced in the three-membered ring because of the non-periplanar conformation of the anti transition state. According to theory, the initial reactant complex can react further via the E2(anti) pathway or SN2 substitution. The barrier to substitution is 2.5 kcal mol−1 and the SN2 pathway dominates over elimination in this system. At the MP2/6-31(+)G∗//HF/6-31(+)G∗ level, the SN2 pathway has a lower activation barrier by 7.3 kcal mol−1 compared with the E2(anti) pathway.

The optimal method for isolating the sesquiterpene lactone britanin from the aerial part of Inula britannica L. (Asteraceae) was developed. Britanin was functionalized by reacting it with methyl mercaptoacetate.

The Diels-Alder reaction of 1-methylcycloprop-2-ene-1-carbonitrile and coumalic acid methyl ester (methyl 2-oxo-2H-pyran-5-carboxylate) gave a 2:1 adduct with endo-syn configuration of both cyclopropane fragments, which was established by X-ray analysis. According to the 1H NMR data, the reaction involves intermediate formation of decarboxylated 1:1 adduct having a cycloheptatriene structure; its isomerization into the corresponding caradiene, followed by addition of the second dienophile molecule, was confirmed by quantum-chemical calculations.

Addition of N-(2-mercaptopropyonyl)glycine to (+)-limonene or (-)-β-pinene in the presence of a Lewis acid involves the mercapto group; simultaneously, the carboxyl function is esterified by ethanol used as solvent. Both reactions give rise to a terpenoid of the menthane structure, which contains, along with a sulfide group, a peptide fragment promising in terms of biologic activity, as well as an ester group.

The1H and13C NMR spectral parameters were found for 3-methyl-3-cyanocyclopropene and 3-phenyl-3-phenyl-3-methylcyclopropene. The proton-carbon coupling constants indicate the acetylenic nature of bonding in the cyclopropene ring.