1,8-Dihydroxy Naphthalene-A New Building Block for the Self-Assembly with Boronic Acids and 4,4'-Bipyridine to Stable Host-Guest Complexes with Aromatic Hydrocarbons.

The new Lewis acid-base adducts of general formula X(nad)B←NCH-CHN→B(nad)X [nad = 1,8-OCH X = CH (), 3,4,5-F-CH ()] were synthesized in high yields via reactions of 1,8-dihydroxy naphthalene [nadH] and 4,4'-bipyridine with the aryl boronic acids CHB(OH) and 3,4,5-F-CHB(OH), respectively, and structurally characterized by multi-nuclear NMR spectroscopy and SCXRD. Self-assembled H-shaped Lewis acid-base adduct proved to be effective in forming thermally stable host-guest complexes, × solvent, with aromatic hydrocarbon solvents such as benzene, toluene, mesitylene, aniline, and -, -, and -xylene. Crystallographic analysis of these solvent adducts revealed host-guest interactions to primarily occur via π···π contacts between the 4,4'-bipyridyl linker and the aromatic solvents, resulting in the formation of 1:1 and 1:2 host-guest complexes.

Intramolecular frustrated Lewis pair mediated approach to the CO bond activation and cleavage of carbon dioxide.

A thermally stable FLP-CO adduct of pronounced nucleophilic properties that forms a range of Lewis acid-base adducts with strong Lewis acids is reported. Upon addition of TfO, it generates a cationic triflate, which undergoes C-O bond cleavage to give the formal FLP adduct of the elusive dication CO.

Carbon monoxide bond cleavage mediated by an intramolecular frustrated Lewis pair: access to new B/N heterocycles selective incorporation of single carbon atoms.

Utilizing an intramolecular frustrated Lewis pair (FLP) decorated with a strongly donating guanidino moiety enabled the formation of a thermally remarkably stable FLP-CO adduct, which at 120 °C underwent CO migration to form an acyl borane. Both compounds underwent rapid CO cleavage in the presence of strong electrophiles leading to the selective formation of a range of new 1,2- and 1,3-benzazaboroles in good yields under mild conditions.

Small Molecule Activation with Intramolecular "Inverse" Frustrated Lewis Pairs.

The intramolecular "inverse" frustrated Lewis pairs (FLPs) of general formula 1-BR -2-[(Me N) C=N]-C H (3-6) [BR =BMes (3), BC H , (4), BBN (5), BBNO (6)] were synthesized and structurally characterized by multinuclear NMR spectroscopy and X-ray analysis. These novel types of pre-organized FLPs, featuring strongly basic guanidino units rigidly linked to weakly Lewis acidic boryl moieties via an ortho-phenylene linker, are capable of activating H-H, C-H, N-H, O-H, Si-H, B-H and C=O bonds. 4 and 5 deprotonated terminal alkynes and acetylene to form the zwitterionic borates 1-(RC≡C-BR )-2-[(Me N) C=NH]-C H (R=Ph, H) and reacted with ammonia, BnNH and pyrrolidine, to generate the FLP adducts 1-(R HN→BR )-2-[(Me N) C=NH]-C H , where the N-H functionality is activated by intramolecular H-bond interactions.

Boronic, diboronic and boric acid esters of 1,8-naphthalenediol - synthesis, structure and formation of boronium salts.

The 1,8-naphthalenediolate [1,8-O2C10H8] supported boronic and boric acid esters of general formula X-B(1,8-O2C10H8), where X = C6H5 (1a), C6F5 (2a), 3,4,5-F3-C6H2 (3a), 2,4,6-F3-C6H2 (4a), 2,6-F2-C6H3 (5a), 2,6-Cl2-C6H3 (6a), 2,4,6-Me3-C6H2 (7a), 2,6-(MeO)3-C6H3 (8a), Bun (9a), MeO (10a), OH (11a) and Cl (13a), were synthesized, NMR spectroscopically characterized, and the solid-state structures of 1a-5a, 8a and 10a determined by X-ray crystallography. The acceptor numbers of 1a-7a and 13a were determined and found to be similar to their catecholate analogues, R-Bcat, indicating similar Lewis acidities of these two classes of boronic acid esters. The reaction of B2(NMe2)4 with 1,8-naphthalenediol, followed by addition of HCl furnished the diboronic acid ester B2(1,8-O2C10H8)4 (16a) in ca.