Propyne-allene mixture

The reaction has been successfully extended to a propyne-allene mixture the corresponding A -isopropenylpyr-roles were isolated as mixtures (Scheme 45) <2000S1585>. 

SYNONYMS mapp gas, methyl acetylene - allene mixture, methyl acetylene - propadi-ene mixture (stabilized), propadiene methyl acetylene, propyne - allene mixture, propyne - pro-padiene mixture. 

Synonyms/Trade Names MAPP gas. Methyl acetylene-allene mixture, Propadiene-methyl acetylene. Methyl acetylene-propadiene mixture (stabilized), Propyne-allene mixture, Propyne-propadiene mixture ... 

METHYL ACETYLENE-PROPADIENE MIXTURE MAPP gas. Methyl acctylcnc>allene mixture. Propyne-allene mixture Strong oxidizers, copper alloys (>67 Cu NA 3.4 11... 

The reaction temperature and time as well as structure of the starting propyne-allene mixture effect slightly on the ratio of pyrroles formed. Only a weak dependence of the regioisomers ratio upon the catalyst nature and propyne pressure (concentration) is observed. The reaction outcome strongly depends on ketoxime... 

The reaction of ethyl methyl ketoxime with propyne-allene mixture, despite the increased temperature (115°C-125°C), remains regioselective (only the methylene... 

Synthesis of pyrroles from ketones (through ketoximes) and propyne-allene mixture, a large-scale side product of hydrocarbons pyrolysis, essentially expands the preparative possibilities of the Trofimov reaction. 5-Methyl-substituted pyrroles, having diverse substituents in the positions 2 and 3, become readily available for the first time. 

L,2-propadiene, allene, CH2=C = CH2, CjH4. Colourless gas prepared by the electrolysis of potassium itaeonate, or by the action of zinc and alcohol on 1,3-dibromopropane. It is easily isomerized to propyne (methylacetyl-ene), and is produced as a mixture with this substance from some reactions. 

Benzofuranyl)pyrroles, 2-(2-thienyl)pyrroles , 2,2 -dipyrroles, 3-(2-pyr-rolyl)indoles , 2-(2-benzimidazolyl)pyrroles and2-(2-, 3- and4-pyridyl)pyrroles were prepared using this method. Reaction of alkynes (for example, propyne) or allene with ketoximes in a superbase system (MOH/DMSO) leads to 2,5-di- or 2,3,5-trisubstituted pyrroles Pyrroles and dipyrroles were synthesized also from corresponding dioximes and acetylene in a KOH/DMSO system It has also been shown that 1,2-dichloroeth-ane can serve as a source of acetylene in pyrrole synthesis. Oxime 52 in the system acetylene/RbOH/DMSO at 70 °C afforded a mixture of three pyrroles 53-55 in low yields (equation 23). The formation of product 53 occurred through recyclization of pyrrolopy-ridine intermediate. ... 

Considerably more work has been reported on the addition of HCI to allenes.73,76 Bismuth trichloride has frequently been added to catalyze these reactions. 1,2-Propadiene affords mixtures of 2-chloro-l-propene, 2,2-dichloropropane,propyne, and l,3-dichloro-l,3-dimethylcyclobutane.75-77... 

Sodium triethylhydroborate reacts with propyne (methylacetylene) with hydrogen evolution even at room temperature.4 In place of pure propyne, a hydrocarbon mixture containing ca. 30% propyne and ca. 30% allene can also be used.4 Only the propyne reacts. 

The lithiocarbon C3Li4 reacts with organic and organometallic substrates to give a variety of highly unsaturated derivatives (Scheme 1). With organometallic halides such as trialkylchlorosilanes, the usual products are tetrasubstituted allenes (2). Alkyl halides often give explosions, but the alkyl sulfates produce mixtures of tetraalkyl derivatives of propyne and propadiene (3). 

The main use of the title reagent is as a precursor of the lithium derivative. l,3-Bis(triisopropylsilyl)propyne is cleanly lithiated by treatment with 1 equiv of n-butyllithium in THF at —20°C (15 min) to what is probably an equilibrium mixture of propargylic and allenic species (1) and (2) (eq 1). The bulky triisopropylsilyl (TIPS) group serves as a controlling group in the addition of (1/2) to electrophiles. 

Irrespective of whether the pnre propyne or allene or their mixtures are employed, the reaction leads to the same resnlts that is not snrprising, since the propynei allene eqnilibrinm ( 4 1) is reached very qnickly in the presence of the superbases. 

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