title: Single-Step Formation of Pyrimido[4,5-d]pyridazines by a Pyrimidine-Tetrazine Tandem Reaction.
abstract: A straightforward synthesis of pyrimido[4,5-d]pyridazines from pyrimidines and tetrazines under basic conditions is reported. Deprotonated, substituted 5-halopyrimidines readily react with variously substituted tetrazines in a highly regioselective manner via a complex reaction pathway, which was supported by DFT calculations. This mechanism leads to the empirically observed regioisomers without going through the conceivable hetaryne intermediate. These results on 5-halopyrimidines led to development of the methodology for preparation of opposite regioisomers based on 6-halopyrimidines.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, 166 10 Prague, Czech Republic.
authors.forename: Juraj
authors.initials: J
authors.lastname: Galeta
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, 166 10 Prague, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Šála
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, 166 10 Prague, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Dračínský
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, 166 10 Prague, Czech Republic.
authors.forename: Milan
authors.initials: M
authors.lastname: Vrábel
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, 166 10 Prague, Czech Republic.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Havlas
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Flemingovo nám. 2, 166 10 Prague, Czech Republic.
authors.forename: Radim
authors.initials: R
authors.lastname: Nencka