Vitomir Šunjić and Krunoslav Kovačević: Organic Stereochemistry in Croatia and Prelog School

Editor: Danijel Namjesnik Published by: Croatian Chemical Society, Zagreb, 2020 ISBN 978-953-8334-00-9 (Hardcover) ISBN 978-953-8334-01-6 (pdf) 310 pages Open access: https://prelog.hkd.hr/ This work is licensed under a Creative Commons Attribution 4.0 International License

Regioselective Transesterifications of Cyclohexanone Derivatives Containing β-Keto and Malonic Ester Moieties

The cyclohexanone derivatives 1–6 containing β-ketoester and α-disubstituted malonic ester moieties in the same molecule were found to undergo regioselective transesterifications with benzyl alcohol giving exclusively β-keto benzyl esters. On the contrary, the acyclic derivatives 9, 10 containing β-ketoester and α-monosubstituted malonic ester groups gave mixtures of transesterified products under the same reaction conditions

Lariat Ethers with Pendant Phenanthridine Units. Synthesis and Complexation of Na- and K-Picrate.

Lariat ethers 12 and 13 with appended phenanthridine fluorophoric units have been prepared as potential fluorescent chemosensor molecules for alkaline metal salts possessing aromatic anions. The starting 8-ethyloxycarbonylamino-6-methylphenanthridine (1) was converted via 2, 3, 6 and 7 to N-(2-tosylethyl)-derivatives 4 and 8 suitable for N-alkylations of diaza- and aza-18-crown-6. However, the alkylations failed, giving the 2-oxazolidinone derivative 5 formed by intramolecular cyclization of phenanthridine N-carbamate derivatives 4 and 8 in basic conditions. The phenanthridine derivative 10 having benzyl instead carbamate protection on 8-amino group successfully alkylated mono- and diaza-crown ethers, giving lariats 12 and 14. Subsequent removal of benzyl protection groups in acidic conditions gave lariats 13 and 15. Lariat 12 was found to form unique Na- and K-picrate complexes with the metal cation bound in the crown cavity and picrate anion intercalated between phenanthridine units

5-bromo- and 5-iodo-N-1-sulfonylated cytosine derivatives. Exclusive formation of keto-imino tautomers

N-1-Sulfonylated cytosine 5 and 5-halogeno-N-1-sulfonylated cytosine derivatives 1 and 2 were synthesized by condensation of silylated cytosine or 5-halogenocytosine bases with tosylchloride in acetonitrile, or by the reaction of cytosine or 5-halogenocytosine bases with tosylchloride in pyridine. The NMR evidences are presented, showing that 1 and 2 form exclusively rare keto-imino tautomers in DMSO-d(6) solution, while N-1-sulfonylated cytosine 5 appears as a common keto-amino tautomer

A Novel Type of Rigid Macrocycle with Bis(3-uracilyl)methane and Hexadiyne Units. The Uracilophane

Synthesis of the first uracilophane 15, constructed from two bis(3- uracilyl)methane units and two hexadiyne bridges connecting uracil N(l)-atoms, is described. The conformational properties of 15 investigated by molecular dynamics revealed low energy conformations with partly or fully stacked phenyl-uracil or phenyl-phenyl pairs

Transcription of gel assemblies of bola type bis(oxalamide)-dicarboxylic acid and -diester gelators into silica nanotubes and ribbons under catalyzed and non-catalyzed conditions

Assemblies of the bola type bis(oxalamide)-dicarboxylic acid and -diester gelators lacking any positive charges or amine groups can be transcribed into silica nanotubes and ribbons by sol-gel polymerizations of tetraethoxysilane (TEOS) either in the presence or absence of benzyl amine as solution catalyst

Syntheses of Amino Alcohols and Chiral C2-Symmetric Bisoxazolines Derived from O-Alkylated R-4-Hydroxyphenylglycine and S-Tyrosine

Chiral C2-symmetric bisoxazolines 1b–f and 2b,c, derived from 4’-O-alkylated R-4-hydroxyphenylglycine or S-tyrosine, were prepared. As intermediates, a series of chiral amino alcohols possessing substituted phenolic groups was prepared and fully characterized

5-Bromo- and 5–Iodo-N-1-sulfonylated Cytosine Derivatives. Exclusive Formation of Keto-Imino Tautomers

N-1-Sulfonylated cytosine 5 and 5-halogeno-N-1-sulfonylated cytosine derivatives 1 and 2 were synthesized by condensation of silylated cytosine or 5-halogenocytosine bases with tosylchloride in acetonitrile, or by the reaction of cytosine or 5-halogenocytosine bases with tosylchloride in pyridine. The NMR evidences are presented, showing that 1 and 2 form exclusively rare keto-imino tautomers in DMSO-d6 solution, while N-1-sulfonylated cytosine 5 appears as a common keto-amino tautomer