4565-13-3Relevant articles and documents
Synthesis of functionalized benzothiophenes and dibenzothiophenes by twofold Heck and subsequent 6π-electrocyclization reactions of 2,3-dibromothiophenes and 2,3-dibromobenzothiophenes
Tengho Toguem, Serge-Mithérand,Malik, Imran,Hussain, Munawar,Iqbal, Jamshed,Villinger, Alexander,Langer, Peter
, p. 160 - 173 (2013/01/15)
Benzothiophenes and dibenzothiophenes were prepared by twofold Heck reactions of 2,3-dibromothiophene and 2,3-dibromobenzothiophene, respectively, and subsequent thermal 6π-electrocyclization. The Heck reaction of 2,3-dibromothiophene and 2,3-dibromobenzo
Synthesis and thermal decomposition of azidovinylbenzothiophenes
Degl'Innocenti, Alessandro,Funicello, Maria,Scafato, Patrizia,Spagnolo, Piero,Zanirato, Paolo
, p. 2141 - 2146 (2007/10/02)
Condensation of 3-azidobenzothiophene-2-carbaldehyde 1 with acetone, diethyl malonate, ethyl acetoacetate and pentane-2,4-dione furnished the 3-azido-2-vinylic derivatives 4a-d in fairly good yields.In refluxing toluene the azides 4a, b, d smoothly gave solely fused pyrrole products, 5a, b, d, whereas azide 4c furnished an isomeric mixture of the cyclized pyrroles 5c and 6.The observed 1H-pyrroles 5a-d and 6 are assumed to occur through aromatization of initially formed 2H-pyrroles 7a-d.Attempted condensation of 2-azidobenzothiophene-3-carbaldehyde 2 with acetone or pentane-2,4-dione gave no vinylic product, but instead resulted in reduction of the azide 2 to the amine 8 or in its conversion into the 1,2,3-triazole adduct 9, respectively.Azido group transfer of 3-styrylbenzothiophene with tosyl azide yielded the ortho-vinyl-sunbstituted α-azide 10, but in poor yield.Thermolysis of the azide 10 gave quantitatively the benzothiopyran 12 clearly ascribable to an initial ring-opening reaction.It is therefore inferred that, in the presence of ortho-vinyl substituent, an α-azidobenzothiophene can exhibit 'normal' ring-cleavage fragmentation, in contrast with previous deoxygenations of 2-nitro-3-vinylbenzothiophenes reported to yield cyclized benzothienopyrroles.Evidence is also presented that, upon thermolysis, the o-azidoaldehyde 1 cleanly affords a benzothienoisoxazole product, whereas the isomeric azide 2 essentially leads to intractable material.
