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Fiberlike Si 3 N 4 was prepared by the carbothermal reduction of diatomaceous earth in a flow of nitrogen and ammonia. Diatomaceous earth, an inexpensive raw material, is composed of 82.5 wt% SiO 2 , 5.69 wt% Al 2 O 3 , and a very small amount of metal oxides (K 2 O, CaO, and Fe 2 O 3 ). Two types of fiberlike Si 3 N 4 were obtained, short needlelike fiber and woollike fiber with Fe droplets at 1350°C

(+)-19-Nordeoxycorticosterone (1) has been synthesised by A-ring construction of the (+)-A-nor-B-trienic steroid (2) obtained enantioselectively from the alkenic benzocyclobutene (12).

Enantioselectivity in the thermolysis of the optically active alkenic benzocyclobutenes 9a–g has been studied, resulting in the development of a novel and efficient route to chiral trans-3a,4,5,9b-tetrahydro-1H-benz[e]indenes 10 and 11.

A convenient and practical route for enantioselective synthesis of the A-nor-B-trienic steroid 2via an intramolecular [4 + 2] cycloaddition of the olefinic ortho-quinodimethane 3 generated in situ by thermolysis of the olefinic benzocyclobutene 4 is reported. This leads to the total synthesis of (+)-11-deoxy-19-norcorticosterone 1 by use of a usual chemical manipulation on intermediate 2.

A short synthesis of an enantiomerically pure des-AB-trienic steroid 11 has been achieved by thermolysis of the optically active alkenic benzocyclobutene 9 obtained by selective nucleophilic addition of an isopropenyl group to the chiral epoxide 5 as a key step.

A concise and practical route to the enantiomerically pure des-A B-trienic steroid 14 was developed by thermolysis of the optically active alkenic benzocyclobutene 13 obtained by selective nucleophilic addition of isopropenyl group to the chiral epoxide 9 as a key step.

The induced diastereoselectivity of the intramolecular Diels-Alder reaction of the trifluoromethyl substituted olefinic o -quinodimethanes 10, 11 , and 21 a – g , generated in situ by the thermolysis of the corresponding benzocyclobutenes 6, 7 , and 20a – g respectively, was investigated experimentally and theoretically. The both cis (ring juncture) and anti selectivity [relative configuration of C 13 and C 17 (steroid numbering) substituents] were enhanced on comparing with that of the corresponding methyl analogs. Semi empirical PM3 calculations have been used to locate the transition structures of the intramolecular Diels-Alder reactions of 10, 11 , and some of 21 . The obtained data were compared with the experimental results of the cycloadditions and showed a good agreement.

Expedient, diasterocontrolled transformations of 1 to the key synthetic intermediate of corynanthe, iboga, and aspidosperma-class of monoterpenoid indole alkaloids which led up to a formal synthesis of (+)-20R-dihydrocleavamine, (-)-eburnamonine, and a total synthesis of (+)-aspidospermidine (2) have been demonstrated.

A novel series of 2-(1,2,4-oxadiazol-5-yl)-1H-indole derivatives as nociceptin/orphanin FQ (N/OFQ) receptor antagonists was discovered. Systematic modification of our original lead by changing the pendant functional groups, linker, heterocyclic core, and basic side chain revealed the structure–activity requirements for this novel template and resulted in the identification of more potent analog with improved potency as compared to the parent compound.

Novel 4-chlorophenylhydrazono-3-oxo-1,2,3,4-tetrahydropyridazino[3,4-b]quinoxalines 10a-c were synthesized by the cyclization of the α-hydrazonohydrazides 8a-c. The chlorination of 10a with phosphoryl chloride afforded 3-chloro-4-[2-(o-chlorophenyl)hydrazino]pyridazino[3,4-b]quinoxaline 12.

Convenient and effective methods for the introduction of a mathylthiomethyl group and other α-thioalkyl group into aromatic compounds are described.

The reaction of the quinoxaline 1 with 4-ethoxycarbonyl-1H-pyrazole-5-diazonium chloride 7 at room temperature gave 3-[α-(4-ethoxycarbonyl-1H-pyrazol-5-ylhydrazono)methoxycarbonylmethyl]-2-oxo-1,2-dihydroquinoxaline 8. The pmr spectrum of 8 in deuteriodimethylsulfoxide supported the presence of two tautomers 8-I and 8-II. Refluxing of 8 in N,N-dimethylformamide or acetic acid resulted in cyclization to afford 8-ethoxycarbonyl-4-oxo-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)-1,4-dihydropyrazolo[5,1-c][1,2,4]triazine 9. Compound 9 was also obtained directly by the reaction of 1 with 7 under reflux in better yield. The reaction of 9 with hydrazine hydrate provided the hydrazinium salt 10, while the reactions of 9 with triethyl and trimethyl orthoformates in the presence of 1,8-diazabicyclo[5,4,0]-7-undecene produced 8-ethoxycarbonyl-4-ethoxyl-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)pyrazolo[5,1-c][1,2,4]triazine 11a and 8-ethoxycarbonyl-4-methoxyl-3-(3-oxo-3,4-dihydroquinoxalin-2-yl)pyrazolo[5,1-c][1,2,4]triazine 11b, respectively. The chlorination of 11a with phosphoryl chloride gave 3-(3-chloroquinoxalin-2-yl)-8-ethoxycarbonyl-4-ethoxylpyrazolo[5,1-c]-[1,2,4]triazine 12, whose reaction with morpholine afforded 8-ethoxycarbonyl-4-ethoxyl-3-[3-(morpholin-4-yl)-quinoxalin-2-yl]pyrazolo[5,1-c][1,2,4]triazine 13.