Pyrroles, 3-alkyl-2-phenyl

Alkyl phenyl ethers (except anisole) Dimethyl pyrroles... 

Indolizines were hydrogenated over Re2S7 catalysts. The pyridine ring was more easily hydrogenated than the pyrrole ring. Phenyl substitution did not prevent complete reduction while alkyl substituents made the reduction more difficult. Nitro groups were reduced to amino groups... 

SCHEME 1.45 Synthesis of 2-phenyl-3-alkyl(phenyl)pyrroles from alkyl phenyl ketoximes... 

SCHEME 1.46 Synthesis of 2-aryl-3-alkyl(phenyl)pyrroles from alkyl aryl ketoximes and acetylene. 

The unique reactivity pattern of alkynyl iodonium salts discussed in Sections II,A.2 and II,D,la can also serve as two-carbon conjunctive reagents in the synthesis of pyrroles, dihydropyrroles, and indoles. Feldman et al. found that combination of alkyl or aralkyl tosylamide anions 101 with phenyl(propynyl)iodonium triflate (102) furnishes the corresponding dihydropyrroles 103 (95JOC7722) (Scheme 28). 

A reaction of JV-alkyl-and N-phenyl-2,5-disubstituted pyrroles with complex 219 at 0 °C gave the best yields of the corresponding pentathiepins 221 under conditions which include treatment with non-premixed sulfur monochloride and DABCO and with complex 220 (2005OL5725 Scheme 117). 

Finally, reaction of 2,4-diphenyl-5(4//)-oxazolone 322 with 4-phenyl-A -tosyl-1-azabuta-1,3-diene was found to be highly dependent on the experimental conditions. At room temperature the sole product was 323 that arises from alkylation of 322 by addition at the imine carbon. However, heating 322 and 4-phenyl-A-tosyl-1-azabuta-1,3-diene gave rise to several products including a 2-pyridone 324, 2,3,6-triphenylpyridine 325, and the pentasubstituted pyrroles 326 and 327. The authors postulated two different reaction mechanisms. Here, both a 1,3-dipolar cycloaddition of the oxazolone and a nucleophilic addition of the oxazolone are possible and that may account for the formation of 324—327. The marked differences in reactivity of 4-phenyl-A-tosyl-l-azabuta-l,3-diene relative to A-alkyl- or A-aryl-1-aza-1,3-dienes was attributed to the powerful electron-withdrawing nature of the tosyl group (Scheme 7.107). ... 

FC acylation and alkylation As pyrroles and furans are not stable in the presence of Lewis acids, which are necessary for FC alkylations and acylations, only thiophene, which is stable in Lewis acids, can undergo these reactions. Thiophene reacts with benzoyl chloride in the presence of aluminium chloride to produce phenyl 2-thienyl ketone. 

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