Gap Cure

The literature data on the application of organosilicon compounds as water scavengers in reactions of carbonyl com- pounds is surveyed. The reactions leading to both carbon–carbon (in particular, aldol-type condensations) and carbon–nitrogen bond formation, the synthesis of iminium salts by elimination reactions and heterocyclizations are considered.

An adhesive composition that contains cyanoacrylate monomers and cyclic or alkyl- or phenyl-terminated linear polydimethylsiloxane is particularly useful in applications requiring flexibility and elasticity. A method of removing, reducing or preventing scar tissue including applying an adhesive composition that contains cyanoacrylate monomer and cyclic or alkyl- or phenyl-terminated linear polydimethylsiloxane.

Die Synthese von purin-ähnlichen biheterocyclischen Ringsystemen wird beschrieben und insbesondere der Aufbau von verschieden substituierten Pyrazolo[3.4-d] pyrimidinen ausgehend von Pyrazolen oder Pyrimidinen besprochen. Synthesewege für Pyrazolo[3.4-c] pyridazine und Pyrazolo[3.4-b] pyridine ausgehend von Pyridazinen und Pyridinen und von Pyrazolo[3.4-b] pyrazinen und Pyrazolo[3.4-d] triazinen ausgehend von Pyrazolen werden angegeben. Als biheterocyclisches Ringsystem mit zwei kondensierten 6-Ringen werden die Pyrimido[4.5-d] pyrimidine erwähnt.

Syntheses of pyrazolo [3,4-d]pyrimidines with an amino group in 3- or 4-position are described. For the preparation of the 3-amino derivatives a 4-chloro-5-cyano-pyrimidine is condensed with various hydrazines. The 4-amino-pyrazolo [3,4-d]pyrimidines are obtained by reacting 3-amino-4-carbethoxy-pyrazoles with formamide, chlorinating thc 4-hydroxy-pyrazolo [3,4-d]pyrimidines, and substituting the halogen by amino groups. Some of the compounds show diuretic and cardiac activity, others inhibit tumor-growth.

The preparation of the paraxanthine, theobromine and theophylline isomers 1,5-; 2,5- and 1,7-; 2,7- and 5,7-dimethyl-4,6-dioxo-4,5,6,7-tetrahydro-pyrazolo[3,4-d]-pyrimidines is described and their structure established. A structurally specific synthesis of the caffeine and isocaffeine isomers 1,5,7- and 2,5,7-trimethyl-4,6- dioxo-4,5,6,7-tetrahydro-pyrazolo [3,4-d]pyrimidines has been realized.

The preparation of the caffeine isomers 1,5,7- and 2,5,7-trimethyl-4, 6-dioxo-4,5,6,7-tetrahydro-pyrazolo[3,4-d]pyrimidines is described and their structures established. The compounds exhibit diuretic and cardiac activity.

Various monosubstituted hydrazines have been reacted with ethoxymethylenemalononitrile to yield the corresponding l-substituted-5-amino-4-cyanopyrazolcs (IV). Treatment of IV with concentrated sulfuric acid gave the corresponding l-substituted-5-aminopyr~zole-4carbosmides (XVI). The structure of 5-amino-1-phenylpyrazole-4-carbosamidewas established by an unambiguous synthesis. The preparation of 1-alkyl- and l-argl-l-aminoayrazolo[3,4-d]pyriniidineshas been accomplished by treating the corre- sponding 1-alkyl(or aryl)-5-amino-4-cyanopyrazole (IV) with boiling formamide.