Photolysis of 11-Methylenepentacyclo-[5.4.0.02,6.03,10.05,9]undecan-8-spiro-3\u27-diazirine. Medium Dependent Reaction

11-Methylenepentacyclo-[5.4.0.02,6.03,10.05,9]undecan-8-spiro-3\u27-diazirine (1) has been synthesized and its photochemical decomposition in different media has been investigated. Irradiation of N2-purged benzene solution of diazirine 1 produced a mixture of four azine-isomers 7a-d. However, photolysis of 1 in pentane gave a mixture of hydrocarbons 6 as the main insertion products and traces of 1,3-bishomopentaprismane (5). The photolytic decomposition of 1 in N2-matrix at -196 °C proved the formation of diazo-compound 8, which upon warm-up gave traces of 1,3-bishomopentaprismane (5)

Photolysis of 11-Methylenepentacyclo-[5.4.0.02,6.03,10.05,9]undecan-8-spiro-3\u27-diazirine. Medium Dependent Reaction

11-Methylenepentacyclo-[5.4.0.02,6.03,10.05,9]undecan-8-spiro-3\u27-diazirine (1) has been synthesized and its photochemical decomposition in different media has been investigated. Irradiation of N2-purged benzene solution of diazirine 1 produced a mixture of four azine-isomers 7a-d. However, photolysis of 1 in pentane gave a mixture of hydrocarbons 6 as the main insertion products and traces of 1,3-bishomopentaprismane (5). The photolytic decomposition of 1 in N2-matrix at -196 °C proved the formation of diazo-compound 8, which upon warm-up gave traces of 1,3-bishomopentaprismane (5)

Novel 1,4-Disubstituted Adamantane Stereoisomers: Synthesis and Spectroscopic Characterization

A series of new 1,4-disubstituted adamantane derivatives [e.g., 1-chloro-4-(carbethoxymethylene) adamantane (3), 1-chloro-4-(carbethoxymethyl)adamantane (4), 1-chloro-4-(2-hydroxyethyl) adamantane (5), 1-chloro-4-(2-bromoethyl)adamantane (6), 1-bromo-4-(2-bromoethyl)- adamantane (7), 1-hydroxy-4-(carbethoxymethylene)adamantane (8), 1-hydroxy-4-(carbethoxymethyl) adamantane (9), 1-acetoxy-4-(carbethoxymethyl)adamantane (10), 1-hydroxy-4-(2-hydroxyethyl) adamantane (11), 1-hydroxy-4-cyanoadamantane (12), 1-hydroxy-4-carboxyadamantane (13), and 1-hydroxy-4-carbmethoxyadamantane (14)] have been synthesized, and their respective syn- and anti-isomers have been separated and identified

Novel 1,4-Disubstituted Adamantane Stereoisomers: Synthesis and Spectroscopic Characterization

A series of new 1,4-disubstituted adamantane derivatives [e.g., 1-chloro-4-(carbethoxymethylene) adamantane (3), 1-chloro-4-(carbethoxymethyl)adamantane (4), 1-chloro-4-(2-hydroxyethyl) adamantane (5), 1-chloro-4-(2-bromoethyl)adamantane (6), 1-bromo-4-(2-bromoethyl)- adamantane (7), 1-hydroxy-4-(carbethoxymethylene)adamantane (8), 1-hydroxy-4-(carbethoxymethyl) adamantane (9), 1-acetoxy-4-(carbethoxymethyl)adamantane (10), 1-hydroxy-4-(2-hydroxyethyl) adamantane (11), 1-hydroxy-4-cyanoadamantane (12), 1-hydroxy-4-carboxyadamantane (13), and 1-hydroxy-4-carbmethoxyadamantane (14)] have been synthesized, and their respective syn- and anti-isomers have been separated and identified

In Vitro Enzymatic Stabilities of Methionine-enkephalin Analogues Containing an Adamantane-type Amino Acid

The enzymatic stability of synthetic methionine-enkephalin peptide analogues containing an unnatural amino acid of the adamantane-type 3-5 was examined in human serum, at 37 °C, and compared with the results of the degradation of the parent endogenous pentapeptide 1 and the tripeptide, Tyr-Gly-Gly (2). Methionine-enkephalin (Tyr-Gly-Gly-Phe-Met, 1) and tripeptide 2 are rapidly degraded in 80 % human serum with half-lives of 12.2 and 23.0 minutes, respectively, preferably by aminopeptidase cleavage of the N-terminal Tyr-Gly peptide bond. Incorporation of the rigid and sterically hindered 1-adamantylglycine moiety into the peptide sequence resulted in increased stability of compound 3, while compounds 4a and 5a were not at all susceptible to the enzymes present in human serum. Strong binding of peptides 3-5 to human serum proteins was demonstrated

Solvent and Temperature Effects in π-Route Cyclization

endo-Bicyclo[3.3.1]non-6-ene-3-carboxylic acid (1) was prepared and the solvent and temperature effects on the n-route cyclization were studied. The stereochemistry of the products strongly depends on the reaction temperature and the solvent used. The interpretation of the mechanism and product distribution based on experimental data is supported by theoretical investigation

Synthesis and Anion Binding Assessment of Novel Adamantane Amidopyrroles

Two new adamantane anion receptors with amidopyrrole side arms were prepared and their anion binding ability in DMSO solutions with TBA salts (Cl–, AcO– and H2PO4–) was investigated by UV/Vis spectroscopy. After calculating the corresponding association constants of receptor-anion complexes, it became apparent that only one amidopyrrole side arm was engaged in complexation. These experimental findings were rationalized using computational tools and the binding mode was proposed. In addition to the found 1 : 1 stoichiometry, we showed that the studied receptors bind oxo-anions (H2PO4– and AcO–) more strongly than spherical halogenide (Cl–) anions

Effect of Adamantyl Compounds on Dynamics of Spin Labelled Multilamellar Liposomes

Interactions of two adamantyl molecules: 3-(adamantan-1-yl)propan-1-aminium chloride (compound A) and 1-hydroxyadamantan (compound B) with multilayer liposomes composed of L-α-phosphatidylcholine, cholesterol and dicetylphosphate, spin labelled with n-doxylstearic acids (n = 5, 7, 10, 12, 16) were investigated. In the presence of aminium salt (A) or alcohol (B) the increased dy-namics of 5-doxylstearic acids and 16-doxylstearic acids in the multilamellar liposomes were determined in the temperature range from 250 K to 295 K. The increased dynamics of 5-doxylstearic acids suggest-ed that both adamantyl compounds influenced molecular motions in the interfacial region of the lipo-some. The increased motional properties of 16-doxylstearic acids, located in the core of the multilamel-lar liposomes, suggested that both adamantyl compounds induced the structural changes in the hydro-phobic core as well

In Vitro Enzymatic Stabilities of Methionine-enkephalin Analogues Containing an Adamantane-type Amino Acid

The enzymatic stability of synthetic methionine-enkephalin peptide analogues containing an unnatural amino acid of the adamantane-type 3-5 was examined in human serum, at 37 °C, and compared with the results of the degradation of the parent endogenous pentapeptide 1 and the tripeptide, Tyr-Gly-Gly (2). Methionine-enkephalin (Tyr-Gly-Gly-Phe-Met, 1) and tripeptide 2 are rapidly degraded in 80 % human serum with half-lives of 12.2 and 23.0 minutes, respectively, preferably by aminopeptidase cleavage of the N-terminal Tyr-Gly peptide bond. Incorporation of the rigid and sterically hindered 1-adamantylglycine moiety into the peptide sequence resulted in increased stability of compound 3, while compounds 4a and 5a were not at all susceptible to the enzymes present in human serum. Strong binding of peptides 3-5 to human serum proteins was demonstrated