Refernces
10.1002/anie.200500466
The study presents the first total synthesis of cavicularin (1), a complex natural product derived from the liverwort Cavicularia densa, which features a strained macrocyclic core with a unique boat-like configuration of one of its arenes. The synthesis involved a radical-induced transannular ring contraction as a key step. Key chemicals used in the study include isovanillin (protected as a dioxolane acetal), 4-fluorobenzaldehyde, sodium borohydride, CBr4/PPh3, neopentyl glycol, DCC, the Herrmann catalyst, DIBALH, and various other reagents for coupling, cyclization, and protection/deprotection steps. These chemicals served to construct and modify the AD and BC ring systems, facilitate cyclization, and ultimately achieve the macrocyclic structure of cavicularin. The study also transformed the macrocyclic precursor into riccardin C, completing the shortest synthesis of this natural product to date.
10.1007/s10600-008-9105-0
The research focuses on the synthesis and bactericidal activity of 6-H(nitro)-9-arylidenedeoxyvasicinones and their perchlorates. Deoxyvasicinone and 6-nitrodeoxyvasicinone were reacted with various aromatic aldehydes, including 3,4-dimethoxybenzaldehyde, isovanillin, 2-bromoisovanillin, 5-bromovanillin, and furfurol, in glacial acetic acid to produce a series of target compounds (2a-e and 3a-i). These compounds were characterized by IR, PMR, and mass spectra. The study also involved the preparation of perchlorates (4a-i) by heating the synthesized compounds in acetic acid in the presence of concentrated HClO4. The synthesized compounds were tested for their bactericidal properties against various gram-positive and gram-negative bacterial strains, showing moderate to low activity.
10.1055/s-0030-1258206
The study presents a copper(I)-catalyzed intramolecular C-O bond-forming cyclization approach for the synthesis of various substituted 1,4-benzodioxines, utilizing a BINOL-CuI complex as a catalyst. This method was effectively applied to the total synthesis of isovanillyl sweetening agents, specifically 5-(2,3-dihydro-1,4-benzodioxin-2-yl)-2-methoxyphenol and 5-(2,3-dihydro-1,4-benzoxathiin-2-yl)-2-methoxyphenol, which are known to be significantly sweeter than sucrose. The process involves a five-step synthesis from isovanillin, yielding the sweetening agents in 15.8% and 14.85% overall yields, respectively. The research also explores the scope and limitations of the method, discussing the impact of different ligands, copper salts, solvents, and bases on the reaction efficiency. The study further proposes a possible mechanism for the Ullmann-type intramolecular C-O coupling cyclization reaction and provides detailed experimental procedures, characterization data, and spectral information for the synthesized compounds.