Stereoselective Synthesis of Isomers of the Naturally Occurring 13-Hydroxy-2,4,9-tetradecatrienoic Acid. Part II [1]

Summary. The stereoselective syntheses of four unsaturated hydroxy fatty acids 13S,2E,4E,9E)- 13-hydroxy-2,4,9-tetradecatrienoic acid, (13S,9Z,11E)-13-hydroxy-9,11-tetradecadienoic acid, (13S,9E, 11E)-13-hydroxy-9,11-tetradecadienoic acid, and (13S,2E,4E,9E)-13-hydroxy-2,4,9,11-tetradecatrienoic acid, are described. Wittig reactions, regioselective oxidation of dialcohol 3, and diastereomerization were used.     

Furan derivatives. Part 13 . Synthesis of thiopyrano[4,3,2-cd]benzofuran

Thiopyrano[4,3,2-cd]benzofuran 9 possessing benzofuran and methylenethiopyran structures in the molecule was synthesized starting from 1-chloro-4-methoxy-2-nitrobenzene 11. Some reactions (formylation, protonation and catalytic hydrogenation) on 9 were examined. The 2-position of 9 was highly reactive toward electrophilic reagents and the furan ring was readily reduced by catalytic hydrogenation with palladium-charcoal. Thiopyrano[4,3,2-cd]benzofuran 9 has both properties of methylenethiopyran and benzofuran.     

13C-NMR. Spectroscopy of Naturally Occurring Substances. XXXV. Labdanic diterpenes

A total carbon shift analysis of several representatives of the labdane diterpene family of natural products is presented. The shift assignment is based on the prior shift designation of some synthetic trans-decalin derivatives.     

1—芳酰基—4—（1‘—N—β—D—吡喃型糖基）氨基硫脲类化合物的合成

通过２,３,４,６－甲－Ｏ－乙酰基－β－Ｄ－吡喃型葡萄糖异硫氰酸酯和２,３,４－三－Ｏ－乙酰基－β－Ｄ－吡喃型木糖异硫氰酸酯与取代的芳基酰肼和亲核加成反应合成了１０个１－芳酰基－４－（１’－Ｎ－２’,３’,４’,６’－四－Ｏ－乙酰基－β－Ｄ－吡喃型葡萄糖基）氨基硫脲和７个１－芳酰基－４－（１’－Ｎ－２’,３’,４’－三－Ｏ－乙酰基－β－Ｄ－吡喃型木糖基）氨基硫脲,所得化合物的结构经元素分析,ＩＲ,     

Condensed pyridazines. Part II. Synthesis of pyrido[2,3-C] pyridazines

The synthesis of some pyrido[2,3-c]pyridazines from 5,8-diehloro-3-methyl-2-oxo-2H-pyrano-[2,3-d]pyridazine (I) is described. Attempted oxidation of 8-amino-3-chloro-1,6-dimethyl-4,7-dioxo-1,4,7,8-tetrahydropyrido[2,3-c]pyridazine (VI) with LTA led only to the deaminated compound VII. Treatment of VI with LTA A in the presence of cyclohexene gave the nitrene adduct XI.     

Facile Synthesis of 1-Hydroxy-5-methoxy-Benzo[f][2,7]naphthyridines

A new route for the synthesis of 1-hydroxy-5-methoxy-benzo[f][2,7]naphthyridines has been developed from easily available precursor 2-chloro-3-formyl quinolines. The 2-methoxy-3-formyl quinolines were prepared and condensed with glycine ethyl ester hydrochloride. This resulted in the formation of an imines, which on cyclization with Dowtherm A yielded 1-hydroxy-5-methoxy-1,2-dihydrobenzo[f][2,7]naphthyridines.     

Annulated benzotetrazine 1,3-dioxides 1. [1,2,5]Oxadiazolo[3,4-f][1,2,3,4]benzotetrazine 2,4,7-and 2,4,9-trioxides

Thermolysis of 6-azido-5-nitro-7-R-benzotetrazine 1,3-dioxides (R = H and Br) gave benzotetrazine 1,3-dioxides annulated with the furoxan ring at the C(5)-C(6) bond. According to the NMR data, these compounds at 297 K are equilibrium mixtures of two isomers with different positions of the N-oxide oxygen atom in the furoxan ring. Full assignment of signals in the ¹³C NMR spectra of the compounds obtained was accomplished. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 133–136, January, 2006.     

A New Chiral Synthesis of Naturally Occurring (-)-(S)-4-Hydroxy-2-pyrrolidinone

4-Hydroxy-2-pyrrolidinoneIisanattractivesimplemolecule.First,ithasservedasakeyintermediateinthesynthesis'ofoxiracetam,adrugusefulforimprovinglearningandmemory.Second,IcanbeeasilytransformedintoantiepilepticandhypotensivedrugGABOB',andhypolipidemicagentcarnitine'.Third,(-)-4-hydroxy-2-pyrro-lidinoneIhasbeenisolated'fromthetoadstollAmanitamuscaria.Itsabsoluteconfigurationhasbeenerroneouslyassigned'as(R).ThefirstchiralsynthesisofthiscompoundhasbeenreportedbyPifferi#.However,notuntil1984didi…     

Synthesis of 3-substituted-2,3,4,5-tetrahydro-1H-naphth[1,2-d]-imidazole-2,4,5-triones and 1-Substituted-2,3,4,9-tetrahydro-1H-naphth[2,3-d]imidazole-2,4,9-triones

Tricyclic compounds with an imidazolinone ring fused to 1,2- and 1,4-naphtoquinones were synthesized by a reaction of 4-amino-1,2-naphthoquinone and 2-amino-1,4-naphthoquinone with electrophilic symmetric and non symmetric diazenes.     

Synthesis of 1-p-Methoxyphenyl and 1-p-Methoxyphenyl-4-methylbicyclo-[2.2.1]heptan-7-one. The Oxidation of 7-Hydroxy-1-p-methoxyphenyl-4-methylbicyclo[2.2.1]heptan-7-carboxylic Acid with Lead Tetraacetate

A simple synthetic route to 1-p-methoxyphenyl and 1-p-methoxyphenyl-4-methylbicyclo [2.2.1]heptan-7-one 6b,a has been developed through benzilic acid rearrangement of the bicyclo[2.2.1]octandiones 2b,a. The oxidation of 7-hydroxy-1-p-methoxyphenyl-4-methylbicyclo[2.2.1]heptan-7-carboxylic acid 3a with lead tetraacetate gives the carbolactone 7a which is also formed by the reaction of the ketone 6a with m-chloroperbenzoic acid.     

Malonylation/Decarbalkoxylation of Furan Derivatives as Key Steps for the Preparation of Nonactic Acid Derivatives. Part II [1]

A malonylation/decarbalkoxylation sequence from 2-substituted furans was investigated in view of developing a scalable synthesis of hydrophobic nonactic acid analogues.     

Malonylation/Decarbalkoxylation of Furan Derivatives as Key Steps for the Preparation of Nonactic Acid Derivatives. Part II [1]

Summary. A malonylation/decarbalkoxylation sequence from 2-substituted furans was investigated in view of developing a scalable synthesis of hydrophobic nonactic acid analogues.     

Studies on v-triazoles. Part II. Synthesis of 9-oxo-1H,9H-benzopyrano[2,3-d]-v-triazoles

Ethyl 1-benzyl-5-chloro-v-triazole-4-carboxylate ( 3 ) undergoes facile nucleophilic displacement of the halogen atom with phenoxide ion to yield aryloxytriazolecarboxylates 4 which debenzylate under hydrogenolytic conditions to N-H triazoles 7 . Saponification and cyclization with either polyphosphoric acid or phosphoric oxide in methanesulphonic acid leads to the novel 9-oxo-1H,9H-benzopyrano[2,3-d]-v-triazole system 9 , members of which have potential as antiasthmatic agents.