Abstract:Optically active 4,benzo [1,2,3]trithiole 5-oxide (3) and 4,9-diethyl[1,4]dithiino [5,6-f]benzo [1,2,3]trithiole 5, 8-dioxide (4) were obtained by the asymmetric oxidation of 6,11-diethyl[1,4]dithiino [5,6-h]benzo-[1,2,3,4,5]pentathiepin (1). The reaction was accompanied by desulfurization and ring-contraction reactions of the pentathiepin ring. Similarly, optically active 4,3]dithiolo [4,5-f]benzo-[1,2,3]trithiole 5-oxide (7) was produced by the analogous asymmetric oxidation of 6,10-diethyl-[1,3]dithiolo … Show more
“…547 Benzotrithioles related to the cytotoxic pentathiepin ascidian alkaloids varacin 548 and lissonclinotoxin A 549,550 have been prepared and optical rotatory properties and crystal structures investigated. 551 Lissoclinotoxins E 650 and F 651 were isolated as mildly cytotoxic components of a Philippine didemnid ascidian. 552 The relative orientation of the aromatic rings of 650 and 651 were deduced, as shown, based upon molecular modeling studies.…”
This review covers the literature published in 2003 for marine natural products, with 619 citations (413 for the period January to December 2003) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (656 for 2003), together with their relevant biological activities, source organisms and country or origin. Biosynthetic studies or syntheses that lead to the revision of structures or stereochemistries have been included (78), including any first total syntheses of a marine natural product.
“…547 Benzotrithioles related to the cytotoxic pentathiepin ascidian alkaloids varacin 548 and lissonclinotoxin A 549,550 have been prepared and optical rotatory properties and crystal structures investigated. 551 Lissoclinotoxins E 650 and F 651 were isolated as mildly cytotoxic components of a Philippine didemnid ascidian. 552 The relative orientation of the aromatic rings of 650 and 651 were deduced, as shown, based upon molecular modeling studies.…”
This review covers the literature published in 2003 for marine natural products, with 619 citations (413 for the period January to December 2003) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (656 for 2003), together with their relevant biological activities, source organisms and country or origin. Biosynthetic studies or syntheses that lead to the revision of structures or stereochemistries have been included (78), including any first total syntheses of a marine natural product.
“…The tricyclic compounds 141 (Figure ) and 16a have both fused trithiole and pentathiepin rings. The former was oxidized with MCPBA 54 or with Ti(OPr i ) 4 / R , R -DET/t-BuOOH 55a. In each case the trithiole ring, but not the pentathiepin ring, was oxidized, four monoxides 142a , b and 143a , b being isolated.…”
Section: 2 Oxidation and Reduction Of Fused Trithiole
Ringsmentioning
confidence: 99%
“…142a , b are nonchiral conformational isomers with a plane of symmetry, while the unsymmetrical 143a , b are diastereoisomers with respect to the pentathiepin ring and the configuration of the sulfinyl group (see also section 5.7). When the closely related compounds 141a were oxidized with the same reagents, the smaller heterocyclic ring was again oxidized preferentially, but this was now accompanied by desulfurization and contraction of the pentathiepin ring to a trithiole 55b 3 …”
Section: 2 Oxidation and Reduction Of Fused Trithiole
Ringsmentioning
“…Conversely, we have reported on the preparation, structure, reactivity, and electrochemical properties of several benzoannelated oligosulfides, benzo[1,2,3,4,5]pentathiepins, and benzo[1,2,3]trithioles. − In these reports, the preparation of 4,8-diethylbenzo[1,2- d :4,5- d ‘ ]bis[1,2,3]trithiole ( DEBBT ) represents one of the most vital results. DEBBT was prepared in good yield in a one-step reaction by treating 2,3,5,6-tetrabromo-1,4-diethylbenzene ( TBDEB ) with elemental sulfur in liquid ammonia at 120 °C (eq 1) .…”
Benzo[1,2,3]trichalcogenoles with two bromine atoms on the benzene ring, 5,6-dibromo-4,7-diethylbenzo[1,2,3]trichalcogenoles (1a) and (1b) (chalcogen: 1a = S; 1b = Se), were first prepared by treating 2,3,5,6-tetrabromo-1,4-diethylbenzene (TBDEB) with elemental sulfur or amorphous selenium in DBU at 140 degrees C (for 1a) and 100 degrees C (for 1b) for 24 h. The structures of 1a and 1b were verified by NMR spectroscopy, mass spectrometry, and elemental analysis. X-ray crystallographic analysis ultimately showed that the substitution reactions of TBDEB proceeded at the two adjacent bromine atoms. To apply 1a and 1b to construction of phthalocyanine derivatives with sulfur or selenium functional groups, 4,5-bis(benzylchalcogeno)-3,6-diethylphthalonitriles (5a) and (5b) as key intermediates were prepared by way of introduction of alkyl groups (2-cyanoethyl or 4-nitrophenethyl groups) on two chalcogen atoms, substitution of two bromine atoms with nitrile groups, and subsequent exchange of alkyl groups with benzyl groups. Compound 5a was treated with lithium in n-pentanol at 100 degrees C for 1 h to produce 2,3,9,10,16,17,23,24-octakis(benzylthio)-1,4,8,11,15,18,22,25-octaethylphthalocyanine (6a). A similar treatment of 5b in n-hexanol at 100 degrees C for 2 h gave phthalocyanine 6b. The structures of 6a and 6b were determined by (1)H NMR spectroscopy and MALDI-TOFMS. X-ray crystallographic analysis of 6a was also performed. The Q-band absorptions (lambda(max)) for 6a and 6b in UV-vis spectra were observed at 755 nm (log epsilon = 5.1) and 757 nm (log epsilon = 5.1), respectively, and their electrochemical properties were verified by cyclic voltammetry in dichloromethane with Ag/AgNO(3) as a reference electrode. Compounds 6a and 6b were further treated with lithium in THF/NH(3) at -78 degrees C and then with dibutyltin dichloride to produce phthalocyanine derivatives 8a and 8b with four dichalcogenastannole rings by way of octachalcogenate phthalocyanines 7a and 7b.
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