It will be also used as catalyst component in the liner cyclization
and oligomerization of unsaturated carbon.
Hence, in our study, 5-(4-methoxyphenyl)-4-[(4-methoxyphenyl)carbonyl]-2-methylpyrazolo[1,5-c]pyrimidin-7(1H)-on (2a) and 5-(4-methylphenyl)-4-[(4-methylphenyl)carbonyl]-2-methylpyrazolo[1,5-c]pyrimidin-7(1H)-one (2b) were synthesized by the cyclization
, involving the reaction of N-aminopyrimidine derivatives (1a, b) with [alpha]-chloroacetone in xylene under reflux for 8 h (Scheme-2) (for details see Experimental).
The thiazepines 114a-g on condensation with [alpha]-bromoacetophenone, in the presence of anhydrous [K.sub.2]C[O.sub.3]/dry acetone and catalytic amount of KI, followed by cyclization
in ethanolic KOH, gave methylene-bisbenzofurano-[1,5]-benzothiazepine derivatives 115a-g (yield% was not reported) and were purified by column chromatography using silica-gel (60-120 mesh)/petrol ether (60-80[degrees]C)  (Scheme 28).
One of the potential problem of using peptide therapeutics is their ability to provoke immunogenicity of host system, as human immune cells have some receptors such as TLRs for sequence specific peptide patterns of foreign peptides this problem has been approached by cyclization
of linear peptides by head to tail cyclization
linking their N and C-terminus of polypeptide sequence and PEGylation .
The investigators identified the proton-catalyzed cyclization
of trans-iso-[alpha]-acids as the quantitatively predominant reaction leading to lingering, harsh bitter tasting tri-and tetracyclic compounds, such as the cocongeners tricyclocohumol, tricyclocohumene, isotricyclocohumene, tetracyclocohumol and epitetracyclocohumol.
Generally, it is apt to be thought that the cyclization
and substitution do not advance at the position occupied by a substituent.
Around 313.9[degrees]C the weight loss of 7% of the composite nanofibres was due to cyclization
of the PAN, which is in agreement with the DSC analysis.
The most commonly used reactions for pyridine synthesis are Chichibabin synthesis, Bonnemann cyclization
, and Cobalt-catalyzed alkyne-nitrile cyclotrimerization, etc.
Included are stereoselective oxidation and reduction methods; stereoselective additions; cyclizations
; metatheses and different types of rearrangements; asymmetric transition-metal-catalyzed, organocatalyzed, and biocatalytic reactions; methods for the formation of carbon-heteroatom and heteroatom-heteroatom bonds like asymmetric hydroamination and reduction amination, carboamination and alkylative cyclization
, cycloadditions with carbon-heteroatom bond formation, and stereoselective halogenations; and methods for the formation of carbon-sulfur and carbon-phosphorus bonds and asymmetric sulfoxidation.
This reaction gave 5 in very good yield and no trace of any macrocyclic bischalcone 7 (a possible product through bimolecular cyclization
of the intermediate 6) Scheme 3).
Availability of 2-aminobenzophenones limits the range of applicability of this reaction; (2) by cyclization
of 4-arylidenepyrazolin-5-ones with anilines  or 5-N-arylpyrazoles with aromatic aldehydes .
The problem is known as strand cyclization
, but Hud and his team discovered that using a molecule that binds between neighboring base pairs of DNA, known as an intercalator, can bring short pieces of DNA and RNA together in a manner that helps them create much longer molecules.