Diin‐Reaktion, XXXIV. Mono‐ und bis‐heterokondensierte Dibenzothiophenchinone: Benzo‐, Furo‐, Thiopheno‐, Selenopheno‐, Telluropheno‐, Pyrrolo‐dibenzothiophenchinone

Abstract

l-Benzothiophen-2,3-dicarbaldehyd (1) gibt mit 2 mol ~thinylmagnesiumbromid ein Diol 2, dessen Oxidation N o-Diketodiinen 3a, b fiihrt. Mit Tris(triphenylphosphin)rhodium(I)chlorid entstehen aus 3a, b die Rhodiumkomplexe 4n, b. Deren Umsetzung mit Acetylenen fiihrt N Mono-heterokondensierten Benzochinonen 5 -8. Mit Chalkogenen, entmalig auch mit Tellur, sowie Nitrosobenzol entstehen Bis-heterokondensierte Benzochinone 9 -15. D i p Reactioa, XXXIVI)Momd Bki-hetemca&ad Beazoquiaoaes: Beazo-, Fura-, Thiop&m+, -, Tellurophena-, m t h i o p h e & m mI-Benzothiophene-2,3dicarbaldehyde (1) reacts with 2 moles of ethynylmagnesium bromide to give a diol2, the oxidation of which leads to the o-diketodiynes 3a, b. With tris(tripheny1phosphine)rhodium(I) chloride, 3n, b yield the rhodium complexes 414 and b. These react with acetylenes to form the mono-heterocondensed benzoquinones 5-8. 4a, b react with chalcogenides and for the first time with tellurium as well as with nitroso-benzene to give the bis-heterocondensed benzoquinones 9 -15. Vor kurzem wurde uber die Moglichkeit berichtet, o-Diketodiin-Verbindungenzur Synthese von Mono-und bis-heterokondensierten Benzochinonen heranzuziehen.kfinden sich Propinoyl-Gruppen in o-Stellung eines heterocyclischen Systems, so gelangt man uber das Zwischenprodukt eines Rhodiumkomplexes zu Heterochinonen. Dies konnte am Beispiel des Furan-, Thiophen-, Pyrrol-und Triazol-Systems gezeigt werden 2-5). Die= Syntheseprinzip laBt sich auch auf das 1-Benzothiophensystem iibertragen.

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…806 In the (Cp)cobaltacyclopentadiene complexes 347 (eq 92), the metal atom can be replaced by sulfur, selenium, or NR, thus completing a [2+2+1] protocol, and producing thiophenes, selenophenes, and pyrroles. 583 The same type of reaction has been carried out with the rhodacyclopentadiene complexes 503 (eq 132) of Mü ller et al 807,808 The chalcogene atom is introduced by reaction with oxygen gas or hydrogen peroxide, elemental sulfur, red selenium, and amorphous thallium, and the nitrogen by reaction with phenylazide or nitrosobenzene. The metal fragment can also be replaced by a carbonyl group on reaction with CO. 809 Complexes of type 503 are further the isolated intermediates in the "diyne-reaction" which follows a [2+2+2] protocol producing (fused) aromatic systems (see below).…”

“…The results have been collected in a review in 1974 815 and a few later publications. 586,807,816,817 According to Scheme 73, a diyne compound 507 is reacted with, in most cases, Rh-(PPh 3 ) 3 Cl. It is suggested that as the first step toward the isolable rhodacyclopentadiene complexes 509 a rhodacyclopropene complex 508 is formed which is π-coordinated to the triple bond of the second alkyne.…”

“…One of the oldest examples of stoichiometric, metal-assisted syntheses of (fused) benzene derivatives following a [2+2+2] protocol is the “diyne reaction” discovered by Müller. The results have been collected in a review in 1974 and a few later publications. ,,, According to Scheme , a diyne compound 507 is reacted with, in most cases, Rh(PPh 3 ) 3 Cl. It is suggested that as the first step toward the isolable rhodacyclopentadiene complexes 509 a rhodacyclopropene complex 508 is formed which is π-coordinated to the triple bond of the second alkyne.…”