6//-Pyrrolo pyridazines

H(22)2269]. In fact, compound 170e coupled with the activated phenyl to give the pyrrolo[3,2-c]cinnoline 173, while compound Ic still coupled with the 4-position to give the pyrrolo-pyridazine 169c. 

The yellow solution of spiro-fluorene-pyrrolo-pyridazine 8.2e in chloroform was irradiated (see procedure for 8.2d), after flushing with argon, in a 13 cm cuvet. The solution turned red-violet with the formation of the betaine form 8.2f. The color of the betaine 8.2f faded with a half life of t /2 = 4.95 s. 

H,3H- Pyrrolo[l, 2-c]oxazole-l, 3-dione, 5,6,7,8-tetrahydro-IR spectra, 6, 978 [2.2](2,5)Pyrrolophane, N-aryl-rearrangements, 4, 209 Pyrrolophanes natural products, 7, 764 synthesis, 7, 771 Pyrrolophanes, N-aryl-synthesis, 7, 774 (2,4)Pyrrolophanes synthesis, 7, 771 Pyrrolo[3,4-c]pyran-4-ones synthesis, 4, 288 Pyrrolopyrans synthesis, 4, 525, 526 Pyrrolopyrazines synthesis, 4, 526 Pyrrolo[l, 2-a]pyrazines synthesis, 4, 516 Pyrrolo[2,3-6]pyrazines Mannich reaction, 4, 504 Vilsmeier reaction, 4, 505 Pyrrolo[3,4-c]pyrazole, 1,3a,6,6a-tetrahydro-structure, 6, 976 synthesis, 6, 1019 Pyrrolopyrazoles synthesis, 5, 164 Pyrrolo[l,2-6]pyrazoles synthesis, 6, 1002, 1006 Pyrrolo[3,4-c]pyrazoles reactions, 6, 1034 synthesis, 6, 989, 1043 Pyrrolo[3,4-c]pyrazolones synthesis, 6, 989 Pyrfolopyridazines synthesis, 4, 517 Pyrrolo[l, 2-6]pyridazines synthesis, 4, 297 6/7-Pyrrolo[2,3-d]pyridazines synthesis, 4, 291 2/f-Pyrrolo[3,4-d]pyridazines synthesis, 4, 291 6/7-Pyrrolo[3,4-d]pyridazines synthesis, 4, 291... 

The synthesis of pyrrolo[3,4-c]pyridazines 20 is achieved by intramolecular aza-Wittig reactions of the phosphazines 19 <95JHC1457>. 

Pyrido[3, 2 4,5]pyrrolo[l,2- Pyrido[3, 4 4,5]pyrrolo[l,2-A]pyridazine <2005W02005013907>... 

Reaction of 3-alkylamino-6,8-dimethylpyrimido[4,5-c]pyridazin-5,7-diones 80 with cyclohexyl and cycloheptylamines afforded novel cycloalkano bis(pyrrolo[2,3-c]pyrimido[5,4-e]pyridazines 81 <06T652>. 

The synthesis of some novel acyclonucleosides involving pyrrolo[2,3-c]pyridazine and a 4-hydroxybutyl side chain has been reported <00H(53)5>. New pyrrolo[2,3-pyrimidines containing an extended 5-substituent, as potent and selective inhibitors of lck (an src-family tyrosine kinase), have been synthesized and tested <00BMCL2171>. 

A second patent application appeared in 2005, in which a series of pyrrolo[l,2-b]pyridazine-5,6-dicarboxylates was disclosed [31]. Several of the described compounds (exemplified by structure 8) were reported to have IC50 values of < 0.5 iM against DGAT-1. Various hydrophobic and amino substitutions at positions 4 and 7, and 2, respectively, were tolerated on the heterocyclic ring, along with heterocyclic replacements for the 6-substituted ethyl carboxylate. 

The nature of aromatic enamines has no substantial effect on the pathway thus, pyrrolo[2,3-d]pyrimidines 265-267 were synthesized in comparable yields under the same conditions using thenoine 213 with fused aminopyrimidines (06MI2). Also new pyrrolo[2,3-d]pyridazines were prepared by the condensation of thenoine 213 with substituted 5-aminopyr-idazines 268 in formic acid followed by alkylation. Spectroscopic studies of 269 and 270 (Scheme 74) were reported. 

Electrophilic attack of a metal complex on one of the nitrogen atoms of 1,2-diazines has been reported to occur in the mechanism of new metal mediated methods to prepare C-N bonds. Pyrrolo-fused pyridazines and phthalazines for instance were synthesized via attack of the 1,2-diazine on a palladacyclobutane intermediate 34 formed via oxidative addition of an alkylidenecyclopropane to Pd(PPh3)2 (Equation 7) <2004JOC3202>. 

N pyrrolo[3,4-d]pyridazine O furo[3,4-d]pyridazine S thieno[3,4-d]pyridazine... 

The potential tautomerism of l,2,3,4-tetrahydro-5,7-dimethyl-6//-pyrrolo[3,4-i/ pyridazine-l,4-diones has been examined by AMI semi-empirical methods <1998JMT(434)7, 1998JMT(427)65, 1998JMT(430)85>. 

The formation of pyrrolo-, furo-, and thieno[2,3- pyridazines has been predicted on the basis of thermodynamic studies <2005JOC998>. 

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