Polycyclic thiophenes from the direct insertion of heterosulfur bridges into vinylarenes, biaryls, and angularly condensed arenes
There are three synthetic methods for direct introduction of a heterosulfur bridging atom into a vinylarene, biaryl, or angularly condensed arene to form a polycyclic thiophene. Two methods employ elemental sulfur, with or without a catalyst (aluminum chloride). The third method, which uses hydrogen sulfide and a heterogeneous catalyst (usually a metallic oxide) at 450 to 630/sup 0/, is reviewed in detail. Thus, results on 20 different substrates (including a number of compounds bearing pyridine rings) are presented. Experimental observations which concern mechanistic aspects of the reaction are summarized and interpreted. For most substrates it is suggested that an ECEC mechanism prevails, whereby an adsorbed sulfide ion attacks a ..pi..-electron-deficient, adsorbed substrate to form a dihydro intermediate, which then undergoes aromatization. The substrate is adsorbed onto the catalyst either via the ..pi..-electrons or n-electrons (for some pyridine compounds). Type of adsorption and/or relative reactivities of ring positions may control isomeric ratios of products. For 2- and 4-vinylpyridines as substrates it is proposed that 1,2-addition leads to ..beta..-pyridylethanethiols and bis-(..beta..-pyridylethyl) sulfides, which undergo thermal cyclization. The sulfur bridging reaction as a laboratory and, also possibly, a natural route to the formation of polycyclic condensed thiophenes found in the environment is discussed. 80 references, 1 table.
- Research Organization:
- Univ. of Oregon, Eugene
- OSTI ID:
- 5818962
- Journal Information:
- Phosphorus Sulfur; (United States), Journal Name: Phosphorus Sulfur; (United States) Vol. 7:1; ISSN PREED
- Country of Publication:
- United States
- Language:
- English
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10 SYNTHETIC FUELS
58 GEOSCIENCES
580400 -- Geochemistry-- (-1989)
ACTINIDE COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALKENES
AROMATICS
AZINES
BIPYRIDINES
BUTADIENE
BUTENES
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COBALT COMPOUNDS
COBALT OXIDES
CONDENSED AROMATICS
DIENES
DOCUMENT TYPES
HETEROCYCLIC COMPOUNDS
HIGH TEMPERATURE
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN SULFIDES
IRON COMPOUNDS
IRON OXIDES
IRON SULFIDES
KINETICS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHENANTHRENE
POLYCYCLIC AROMATIC HYDROCARBONS
POLYENES
PYRIDINES
QUINOLINES
REACTION KINETICS
REVIEWS
SILICON COMPOUNDS
SILICON OXIDES
STYRENE
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE DEPENDENCE
THORIUM COMPOUNDS
THORIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRIPHENYLENE
YIELDS