Deep molecular baskets - convergent syntheses of calix[4]naphthalenes via directed ortho metallation and Suzuki-Miyaura coupling reactions

• Main Author: Chowdhury, Sultan, 1968-
• Other Authors: Memorial University of Newfoundland. Dept. of Chemistry
• Format: Thesis
• Language: English
• Published: 2001
• Subjects: Calixarenes > Synthesis; Supramolecular chemistry; Ullmann; Newfoundland studies; University of Newfoundland
• Online Access: http://collections.mun.ca/cdm/ref/collection/theses3/id/43269

Thesis (Ph.D.)--Memorial University of Newfoundland, 2002. Chemistry Bibliography: leaves 221-233 Calix[4]naphthalenes are a new class of compounds which are analogous to the better-known calix[4]arenes, but have deeper cavities. These compounds, especially the endocalix[4]naphthalenes e.g., 31 can behave as "molecular baskets" in their abilities to complex with neutral guest molecules such as [60]fullerene. This thesis describes the synthesis of such deep molecular baskets. Calix[4]naphthalene (31) was synthesized by self-condensation reactions of 6-fert-butyl-3-(hydroxymethyl)-2-naphthol (29). Various Lewis acids were evaluated in order to obtain 31 in higher yield. Conformational properties of 31 were studied by VT-1H NMR experiments in two different deuterated solvents. Alkyl ether derivatives (41a-41b) of 31, and also teff-butylcalix[4]naphthalene-1,3-crown 42 were synthesized, and all compounds were shown by NMR experiments to exist in cone conformations. -- A synthetic route toward the synthesis of the C^-symmetrical X-12" endo calix[4]naphthalenes e.g., 35 allowed us to evaluate the efficiency of the Suzuki- Miyaura coupling reactions for various benzylic halides and bromomethylnaphthalenes with phenyl- and naphthylboronic acids. Directed ortho Metallation (DoM) reactions using both n-butyl- and tert-butyllithium were evaluated for the introduction of various functional groups ortho to the hydroxy! group of 2- naphthol, bis(2-hydroxy-1-naphthyl)methane and their derivatives. -- Synthesis of calix[4]naphthalene (35) was achieved using both acid- and base-induced condensation reactions of compound 98 and aqueous formaldehyde solution. Various alkyl ether derivatives (113a-113d) of 35 were obtained, and their conformational properties were studied by NMR experiments. The X-ray crystal structure of 113d revealed that it exists in a cone conformation as a clathrate containing two molecules of toluene located in its hydrophobic cavity. -- Calix[4]naphthalene (114), an example of an encto/exo-type calixnaphthalene was synthesized using "2+2" Bdhmer condensation conditions. Considerable effort was expended to synthesize endo calix[4]naphthalenes (78-80), and other calixarenes containing mixed benzene and naphthalene units (e.g., 116) via "2+2" and/or "3+1" Bdhmer conditions. Other unsuccessful attempts were made to synthesize all the possible isomers of endo calix[4]naphthalenes (35a-c and 107) using Suzuki-Miyaura coupling reactions. -- Several approaches towards modifying the lower rim of calixarenes were undertaken in order to deepen their cavities. The hydroxyl groups of 2 were derivatized to triflates 118-121 and also to nonaflate 125 in order to evaluate Suzuki- Miyaura, Stille and Pd-catalyzed carbonylative reaction conditions. The first successful syntheses aryl ether derivatives (131-134 and 137-143) of 2 were achieved using either Nucleophilic Aromatic Substitution (SnAr) or Ullmann ether conditions.