2.2.3.4.5- Pentamethyl-27/-pyrrole

Azaferrocene reacts with aromatic hydrocarbons in the presence of aluminium chloride, giving rise to the cationic complexes of the type (Ti -arene)(Ti -cyclopenta-dienyl)iron(l+) isolated as BF4 salts [87JOM(333)71]. The complex 28 is obtained by reaction of the sulfane compound [Cp(SMc2)3Fe]BF4 with pentamethyl-pyrrole [88AG(E)579 88AG(E)1468 90ICA(170)155]. The metallic site in this center reveals expressed Lewis acidity (89CB1891). 

A small amount of this mixture can also be obtained when the isomeric 3-oxatetracy-clo[3.1.1.02,4.06,7]heptene is heated to 145°C. The major product, however, is 2-oxabi-cyclo[3.2.0]hepta-3,6-diene.113 2,3,5,6,9-Pentamethyl-4-oxa-9-azatetracyclo[5.3.0.02,6.03 5]dec-l(7)-ene-8,10-dione readily isomerizes to the corresponding oxepino[4,5-c]pyrrole. 14... 

Pyrrole, 1,2,3,4,5-pentamethyl-benzoylation, 4, 220 Pyrrole, 2,3,3,4,5-pentamethyl-reactions, 4, 83 Pyrrole, 1-pentyl-mass spectra, 4, 21-22 Pyrrole, phenyl-benzoyl oxidation, 4, 260 conformation, 4, 192... 

The derived quaternary salts (e.g., 246) give anhydro compounds (e.g., 247) on treatment with alkali. -Pentamethyl-pyrrolenine (2,3,3,4,5-pen tain ethyl-3//-pyrrole) undergoes quantitative conversion to the -isomer (2,2,3,4,5-penta-methyl-2//-pyrrole) either on heating (>200C) or in 1 M HC1 at room temperature. 3//-Indoles also undergo an acid-catalyzed rearrangement (e.g., 248 249), known as the Plancher rearrangement. 

The use of ozonolysis to establish the structure of pentamethyl-2//-pyrrole (1) was described earlier (Section II,A,2).16 Treatment of pentachloro-2f/-pyrrole with silver(I) fluoride gave in addition to the fluoride (143), the bis(acid fluoride) of dichloromaleic acid.57 Oxidation of the diamino ester 155 with lead tetraacetate led to the cyanoimine 156, which in turn was cyclized to the pyrimidine 157 (Scheme 54).137... 

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