Letters in Organic Chemistry - Volume 3, Issue 8, 2006

2-Arylbenzoxazoles, 2-arylbenzimidazoles and 2-arylbenzothiazoles were directly synthesized from substituted 2-aminophenols and aldehydes in the presence of activated carbon (Darco® KB or Shirasagi KL) in xylene under an oxygen atmosphere. Hantzsch 1,4-dihydropyridines and 1,3,5-trisubstituted pyrazoles were also oxidized to the corresponding aromatic compounds by the aid of activated carbon in both acetic acid Read More

Bifluorenylidenes were synthesized in two steps, by conversion of fluorenones to fluorenethiones followed by reductive dimerization of the latter in boiling benzene. Treatment of 12H-dibenzo[b,h]fluoren-12- one (5) with Lawesson's reagent (LR) in boiling toluene gave12H-dibenzo[b,h]fluorene-12-thione (6). Heating a benzene solution of 6 under reflux gave 12-(12'H-dibenzo[b,h]fluorene-12'-ylidene)-12H-dibenzo[b,h] fluorene (4 Read More

Styrene was polymerized via thermolyses of N-4-R-benzyl-N-nitrosoamides in heptane, 1- chloroheptane, ethylene dichloride, and DMSO at various temperatures and the glass transition temperatures and MWs obtained. The data show that the polymer yield depends upon solvent, the 4-R-substituent, and temperature. In contrast, both the glass transition temperatures and the MW are insensitive to these factors.

Two clean and efficient methods for the synthesis of 14-alkyl and 14-aryl-14-H-dibenzo[a,j] xanthenes are described: (1) in aqueous media, using p-dodecylbenezenesulfonic acid (DBSA) as the catalyst (20 mol%), under heat conditions. (2) Under solvent-free condition, using p-toluene sulfonic acid (p-TSA) as catalyst and in microwave irradiation.

The allylindium reagents obtained from metallic indium and allyl bromides, in THF, couple chemioselectively to the carbonyl group of α,α- dichloroketones to afford 1,1-dichloro-2-organyl-pent-4-en- 2-ols in good to excellent yields.

The substituted cyclopentadiene endoperoxides were observed to form their corresponding substituted pyrylium cations in the presence of perchloric acid.

Reaction of 2,7-(2-thienyl)fluoren-9-one with Lawesson's reagent produces a low HOMO-LUMO gap 1,3-dithietane that can be electrochemically polymerised to yield a low band gap poly(fluorene-co-dithiophene) copolymer.

A simple and efficient method for the oxidative homocoupling of terminal alkynes to symmetrical 1,4-disubstituted 1,3-diynes has been developed using copper(I) iodide in a task specific basic ionic liquid, [bmim]OH under atmospheric condition without requiring any palladium compound, amine base, oxidant and organic solvent.

A novel and convenient synthetic approach to ubiquinone-10 was reported via the SN2'-type nucleophilic displacement reaction between copper-catalyzed Grignard reagent and the secondary allylic acetate, which was suitable for the large-scale production of ubiquinone-10.

The enantioselective bioreduction of alpha-substituted-acetophenones 1,2 was carried out with cells of fungi to give the corresponding chiral alcohols in good yield and high enantioselectivity (up to 99%). The chiral alcohols 3 and 4 obtained by this methodology are important intermediates for the asymmetric syntheses of chiral drugs. The enantioselectivity presented by several fungal strains was anti-Prelog.

Selective reduction of the nitrile in methyl 2-cyanomethyl-3-nitrobenzoate with DiBAL-H at low temperature, followed by cyclisation in situ gave 5-nitroisoquinolin-1-one, leading towards the lead PARP-1 inhibitor 5-AIQ. However, increasing steric bulk at the methylene switched reduction to the ester only, giving the corresponding benzaldehyde. Surprisingly, increasing steric bulk in the ester also allowed reduction of the ester pri Read More

The chemical functionalization of diamond (100) by facile oxidation and complexation with transition metal oxide, OsO4, is confirmed by our theoretical calculations. Interestingly, the [2+2] and [3+2] addition pathways can both possibly exist on diamond (100), particularly for the base-catalyzed process. The osmylation of diamond (100) would present a new strategy for oxidation of diamond (100) as well as a starting p Read More

N-Chlorodiazinones were newly synthesized by reaction of diazinones with sodium hypochlorite in aqueous media in excellent to good yields. Yields of the products varied depending upon the pH value of the solution: in many cases the N-chlorination proceeded more smoothly at pH7 than at pH12.

The ring transformation of 1-methyl-3,5-dinitro-2-pyridone afforded 2-aryl-5-nitropyridines upon treatment with aromatic ketones in the presence of ammonium acetate. In reactions with aliphatic ketones, 2,6- disubstituted 4-nitroanilines could be prepared in addition to corresponding 2,3-disubstituted 5-nitropyridines. In these reactions, dinitropyridone behaved as the synthetic equivalent of unstable nitromalonaldehyde.

The synthesis of novel S-bisphosphonates (S-BPs) by two different approaches is described. Hydrolysis of the resulted BPs with conc. HCl afforded the corresponding thio-bisphosphonic acids. The properties of these compounds in the rat adjuvant model of arthritis, and the synthetic routes to these and related compounds are detailed.

Thermal condensation of acetals with different thiophosphoramides at 120-160 °C resulted in the formation of the corresponding N-thiophosphoryl imines in good to excellent yield (80-98%) with high purity (>95%, determined by 1H NMR and elemental analyses).

3-(4-Iodophenoxy)-tris(2-nitrobenzenesulfonyl)-1,4,7-triazacyclodecane (5a) was synthesized by a Mitsunobu reaction between pernosylated diethylenetriamine (4a) and 1,3-bis(trityloxy)propan-2-ol (2). 5a served as a key intermediate in the preparation of MRI contrast agents allowing biomolecule labeling both in solution and on solid phase.