Asymmetric Syntheses of the Macrocyclic Spermine Alkaloids (−)-(S)-Protoverbine, (−)-(S)-Buchnerine, and Their Naturally Occurring Congenial Alkaloids

Enantioselective synthesis of gem-disubstituted N-Boc diazaheterocycles via decarboxylative asymmetric allylic alkylation

“…If decarboxylative alkylation could be achieved with the versatile tetrahydropyrimidin-2-one scaffold, a broader range of chiral β 2,2 -amino acids might be accessible (Scheme 3C). Additionally, tetrahydropyrimidinones may be reductively transformed into hexahydropyrimidines, which are found in bioactive molecules such as the antibiotic hexetidine and the macrocyclic natural product verbamethine 14…”

Functionalisation of Macroheterocycles with Preserving and Changing Their Sizes

“…The presence of additional functional groups at one or several nitrogen atoms broadens chelating properties and allows regulating solubility and behaviour in solutions. [22][23][24][25][26][27] N-Functionalized triazamacrocycles that are prepared mostly by N-alkylation reaction [28][29][30][31] are especially attractive compounds to prepare selective ligands that coordinate transition metals.…”

“…The presence of unequal nitrogen atoms in the resulting cyclic aminodiamide (19) allows carrying out alkylation chemoselectively and obtaining monosubstituted amine (15) after reduction of amide groups (Scheme 4). Synthesis [33] of two optically pure ligands (20) and (21) containing the L-lactic acid residues in side chains and used for coordination of Mn 2+ ion included successive treatment of cyclic triamines (23) and (24) obtained from acyclic precursors (18) and (22) [34] with K 2 CO 3 base in the polar aprotic solvent DMF and bromodiester (26) that is a product of chemoselective transformations of L-lactic acid (25) (Scheme 5).…”

“…UV spectrum, fluorescence, thermal stability, volatility, etc.). Particularly, 1,4,7,10-tetraazacyclodecane (cyclen) (31) from bis(2-aminoethyl)amine (22) [36,37] and 1,4,8,11-tetraazacyclotetradecane (cyclame) (32) [38] are used as ligands for selective binding of metal ions into very stable complexes (Scheme 7).…”