3- -pyrrolo

Pyrazolo[4,3- ]pyrrolo[l,2- ]pyrazines were obtained by cyclodehydration of amide derivatives of pyrrolopyrazoles <2005M217>. 

Angular fused imidazolo[4,5-3]pyrrolo[3,2-rf]thiopyrans and their corresponding sulfoxides and sulfones have been described previously <1996CHEC-II(8)967>. 

Khodairy and El-Sayed synthesized thieno[2,3-3]pyrrolo[3,2- ]thiopyrans 449 by reaction of the 4-chlorophenyl-methylenemalononitriles 447 with CS2 and 2 mole equiv of ethyl chloroacetate under phase transfer conditions (Equation 122) <2001SC475>. 

Several bis-heterocyclopyridines have been previously demonstrated to have various central nervous system effects <1996CHEC-II(8)967>. Pyrrolo[l, 2- ]thieno[3,2-f ]pyrazines have been demonstrated to be high-affinity ligands for 5-HT3 receptors <1996JME2068>. Pyrazolo[4,3- ]pyrrolo[ l,2-tf]pyrazines have moderate antibacterial and antifungal activity <2005M217>. 

This class of tricyclic compound is dominated by the 377-pyrrolizines (systematically named 3//-pyrrolo[l,2- ]-pyrroles) and related systems, which are fused to another six-membered heterocyclic ring (Figure 1). 

The amino pyrrole 29 derived from the reaction with phenylhydrazine <1998JOC9131> was found to undergo an acid-catalyzed intramolecular condensation with the carbonyl present to give the 3//-pyrrolo[l,2-A pyrazole 30 ring system in a good yield (75%) (Equation 2). 

A synthesis of l,3-pyrrolo[l,2-f]imidazoles 148 has been obtained by reacting 147 with isocyanates in THF under reflux for 4h in the presence of DBU. This reaction gave high yields of l,3-dioxo-l,2,3,4-tetrahydropyrrolo[l,2-f]-imidazoles (Equation 20) <2004JOC9313>. 

Dimethyl-3,5-dimethyl-l//,3//-pyrrolo[l,2-r ][l,3]thiazole-6,7-dicarboxylate 399 (R = H) was prepared from cysteine 396 using the method developed of Padwa et al. <1989JOC644>. The thiazolidine carboxylic acid 397 (R = H), obtained by reaction of the cysteine with formaldehyde, was heated in the presence of acetic anhydride and DMAD to give the sulfide 399 by dipolar cycloaddition of the acetylene to the intermediate dipole 398 (Scheme 59) <2002J(P1)1795>. 

The trivial name 3//-pyrrolizine has been proposed and widely used instead of the systematic name 3//-pyrrolo[l,2-a]pyrrole (1) the numbering is shown with the formula.1... 

The indolo[2,3- ]pyrrolo[3,4-c]carbazolo alkaloids (such as 238 and 240) represent an interesting class of compounds that exhibit diverse biological activities and can be obtained through the following procedure (03JOC8008). 

The results from this preliminary study demonstrated the reality of effecting the regioselective oxidative functionalization of simple 8-oxo-l//-pyrrolo[l,2-a]indoles as a function of the electronics of the C-9 ring substituent. Access to the C-l-substituted ethers 89a-c and tetrahydro-3//-pyrrolo[l,2-a]indole 86 allows for an entry into the mitosenes that was not previously possible.68... 

Butyl-5-formylmethyl-l,7-naphthyridin-6-amine (7) underwent intramolecular cyclization to give 5-butyl-3//-pyrrolo[3,2-/] 1,7 naphthyridine (8) (acidic conditions 72% no details).132... 

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