Synthesis of Naphtho[2,3-b]- and Naphtho[1,2-b]-fused Thieno[2,3-d][1]benzoxepins and Thieno[2,3-d][1]benzothiepins (original) (raw)
Related papers
Green synthesis of thiophenyl-1,4-naphthoquinones
2012
Department of Chemistry, University of Delhi, Delhi--11 0 007, India Organic Building Materials Division, CSJR-Central Building Research Institute, Roorkee-247 667, Uttar Pradesh, India E-mail : pct866@yahoo.com Manuscript received 29 March 2011, revised 23 August 2011, accepted 19 September 2011 Reaction of 1,4-naphthoquinones adsorbed on neutral alumina to thiophenols in ambient conditions gave respective mono thiophenyl 1,4-naphthoquinones regioselectively in quantitative yield. The solvent free synthesis and quantitative conversion makes the process practical method.
ChemInform, 2003
The synthesis of 3-amino-2-methoxycarbonyl-4,7-dimethoxybenzo[b]thiophene (5) and benzothieno[3,2d][1,3]oxazin 15 from 3,6-dimethoxy-2-nitrobenzaldehyde (1) is reported. Benzo[b]thiophene-4,7-quinones 9 and 10 were prepared in good yields by oxidative deprotection of the corresponding dimethoxybenzothiophenes 8 and 7. Cycloaddition reaction of quinone 8 with 1-(E)-trimethylsilyloxy-1,3-butadiene followed by acid-induced aromatization provides access to naphtho[2,3-b]thiophene-4,9-quinone 13 and 14. The in vitro activity of the new quinones against Leishmania amazonensis and human-T-cell leukemia virus type 1 (HTLV-1) is reported.
CHEMICAL & PHARMACEUTICAL BULLETIN, 2002
The synthesis of 3-amino-2-methoxycarbonyl-4,7-dimethoxybenzo[b]thiophene (5) and benzothieno[3,2d][1,3]oxazin 15 from 3,6-dimethoxy-2-nitrobenzaldehyde (1) is reported. Benzo[b]thiophene-4,7-quinones 9 and 10 were prepared in good yields by oxidative deprotection of the corresponding dimethoxybenzothiophenes 8 and 7. Cycloaddition reaction of quinone 8 with 1-(E)-trimethylsilyloxy-1,3-butadiene followed by acid-induced aromatization provides access to naphtho[2,3-b]thiophene-4,9-quinone 13 and 14. The in vitro activity of the new quinones against Leishmania amazonensis and human-T-cell leukemia virus type 1 (HTLV-1) is reported.
1H-naphtho[2,1-b]thiete and 2H-naphtho[2,3-b]thiete- synthesis and reactivity
Tetrahedron Letters, 1994
D-55099 Mains Germany Abstrack The title compounds 4 and 8 sre obtained by flash vacuum pyrolysis of the corresponding hydroxymethylthionsphthols 3 and 7. Whereas 4 shows a smooth ring opening on heating, 8 is therm&y stable but reacts photochemically. The different behavior is explained on the basis of an MNDO calculation. The valence isomers 4' and 8' mprcsent thioquinonemethides. which are highly reactive components in [12x + 2z]cycloaddition pmcesses (4 4 9,10,11; 8-9 12). 2H-Benzo[b]thiete and its derivatives proved to be very useful and versatile reagents for tbe preparation of heterocyclic ring compounds containing sulfur and possibly further hetcroatoms.1*2 We report hue on the synthesis and the cycloaddition reactions of lH-naphtbo[2,1-blthiete (4) and the isomeric 2H-naphtho[2,3-blthiete (8). 2-Hydroxynaphthalene-l<arbaldehydc (1) is transformed with N,N-dimcthylthiocarbsmoyl chloride to an O-ester which rearranges in a Newman-KwaR reaction3v4 to the S-ester 2. Reduction of both functional groups furnishes the thionaphthol3 and cyclization by FVP (flash vacuum pyrolysis)5 finally leads to the target compound 4. CHO CHO 0 OH 1) CI-CS-N(CH3, DMF / DABCO 2) A(lSO-160°C) 83 % 3 4 The isomcric compound 8 can bc obtained on a principally similar route. Ethyl 3-hydmxynaphthalene-2carboxylate (5) is transformed to the S-ester 6. Reduction with lithium ahuninium hydride yields the thionaphthol7 and FVP leads to the formation of 8. Compaxed to 3,7 is much less sensitive towards selfcondensation, thus a quantitative yield can bc obtained for the l.kliiation 7-8. In both pymlyses Hz0 is extruded-and not H2S, which would result in an oxete system or the corresponding quinonemethide.