Pyridazines, 1,2,3,6-tetrahydro-, synthesis

H-Pyrazolo[ 1,2-u]pyrazol-4-ium chloride, 2,3,6,7-tetrahydro-synthesis, 6, 1012 Pyrazolopyridazines synthesis, 5, 322, 326 tautomerism, 5, 309 Pyrazolo[ 1,2-a]pyridazines hydrogenation, 5, 328 reactions... 

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... 

An efficient asymmetric synthesis of (3S)-2,3,4,5-tetrahydro-3-pyridazine-carboxylic acid (4) has been developed (93CC1179]. 

The Ma group devised a facile, an inexpensive, and a metal-free synthesis of pyridazino[4,5-l>][l,4]thiazine-diones 27 via a Smiles rearrangement, obtaining the desired products in high yields (Scheme 11) (13TL3253). Optimal reaction conditions were determined to be treatment of 4,5-dichloro-2-(tetrahydro-2f/-pyran-2-yl)pyridazin-3(2fJ)-one 28 with an N-substituted mercaptoacetamide 29 at room temperature in the presence of cesium carbonate as the base and N,ALdimethylformamide (DMF) as the solvent. The authors foresee future applications of this method to the preparation of biologically active compounds. 

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