Zhi-Tang Huang

Heterocyclic Ketene Aminals

Heterocyclic ketene aminals are presented in view of their synthesis, reactions and applications in the preparation of fused heterocycles

Synthesis of new chromogenic calix[4]crowns and molecular recognition of alkylamines

Abstract A new type of calix[4]crown containing ester group 3 has been synthesized and selectively nitrated to give 4 or ipso-nitrated to give 6. By nitration a novel calixcrown 5 containing a quinone segment was obtained. These nitrated calixcrowns have been used as chromogenic hosts for complexing alkylamines and the factors affecting recognition are discussed.

A facile ring cleavage of cyclic ketones. Synthesis of 9-(alkoxycarbonylalkyl)pyrido[1,2-a]pyrimidines

Abstract 2-(Hexahydro-2-pyrimidinylidene)cycloalkanones 1 react with ethyl propiolate in alcoholic solution to give 9-(alkoxycarbonylalkyl)-pyrido[1,2-a]pyrimidines 3 via ring cleavage of cyclic ketones.

Synthesis of chiral calix[4]arenes bearing tartaric ester moieties

Abstract The synthesis of chiral calix[4]arenes with tartaric acid ester moieties has been achieved by the reactions of tartaric ester chloroacetates with calix[4]arenes in moderate yields. All the chiral calix[4]arene derivatives are in a cone conformation according to the 1 H NMR doublet–doublet pattern of the protons of the methylene groups between the phenol rings. The results of NMR and specific rotations indicate that the molecules have C 2 symmetry with asymmetric features.

Synthesis of glucosylated 1,2,3-triazole derivatives.

A series of potential bioactive compounds, 1-glucosyl-4-heterocyclyl-5-(p-substituted-phenyl)-1,2,3-triazoles , were synthesized. Highly stereoselective products were obtained in good yield. Primary activity screening showed that this type of N-glucosylic compound possessed antitumour and antiviral activities.

New Synthetic Method of p-Nitrocalixarenes

Abstract Calixarenes 1 were directly nitrated with potassium nitrate and aluminum chloride to give p-nitrocalixarenes 2 in good yields. Formation of p-nitrocalix[4]arene (2a) from reaction of p-bromomethylcalix[4]arene (3) with silver nitrate is also described.

The self-assembly of calix[4]arene derivatives based on an A-T base pairing

Abstract Calix[4]arene derivatives with one adenine or thymine sidearm have been synthesized and their self-association characteristics which depend on solvent, temperature and concentrations are described. Mainly Watson–Crick A-T base pairing in these systems was detected using 1 H NMR and ESI-MS.

Selective Etherification of Calix[4]arenes

Abstract Calix[4]arenes 1 or 2 react with alkyl halides and aqueous potassium hydroxide in the presence of PEG as phase transfer catalyst at room temperature to give the selectively distally dietherified product 3 or 4 in excellent yields. While at the same reaction conditions, calix[8]arene 5 give the fully etherified product 6.

The Regiospecific N-Benzylation of Heterocyclic Ketene Aminals

Abstract In the presence of sodium hydride, benzoyl-substituted heterocyclic ketene aminals 1 reacted with benzyl chloride 2 to give exclusively the N-benzylated products 3 in moderate yields.

SYNTHESIS OF ACETYL-SUBSTITUTED HETEROCYCLIC ENAMINES AND THEIR REACTION WITH DIETHYL AZODICARBOXYLATE

Abstract Acetyl-substituted heterocyclic enamines 4 were synthesized from lactim ethers 2 and acetylacetone through condensation and deacetylation reactions, and they, along with the ester-substituted heterocyclic enamines 6, reacted with diethyl azodicarboxylate to afford C-adducts 7 and 8 in excellent yields.