Pyrazolidines 1,3-diamines

The addition of a phenylcerium reagent 0 PhCeCl, ) in tctrahydrofuran to the pyrazoline 4 at — 78 C using an equimolar ratio of cerium(III) chloride, phenyllithium and pyrazoline (CcCI3/ Cf,H,I-i/4 1 1 1) exclusively provides the desired pyrazolidine 5 in good yields (75-94%). This product can be converted to the diamine 3a (R = H) and subsequently into numerous N-sub-stituted derivatives of 3a (e.g.. 3b R = CH3) by means of simple standard procedures23. 

Pyrazolidines (172) can be transformed into diamines (173) by Raney Ni the d,l stereochemistry is preserved. 

Diimines 1 react with sulfur dichloride or disulfur dichloride to give the 1,2,6-thiadiazines 2aj.23 When compounds 1 are treated with thionyl chloride, the 1,2,6-thiadiazine S-oxides 3a-l are formed.23,24 On heating in toluene to 90°C, compounds 2a-j are converted into the pyrazoles 4 by extrusion of sulfur. The pyrazoles 4 can also be obtained by heating the diimines 1 in pyridine for 8 hours with sulfur dichloride, disulfur dichloride, or thionyl chloride. In contrast, the tetrahydro-l,2,6-thiadiazines23 obtained from 1,3-diamines and sulfur dichloride cannot be converted to pyrazolidine derivatives by extrusion of sulfur. When compounds 2 a j or 3a-l are heated at 60 °C in tetrahydrofuran containing 6M potassium hydroxide, the starting materials 1 are recovered. 

N-Amino-inperidin 20,89,125, II55. 4-Amino-piperidm 22 IOM, II320. Athylen.trimethylen-diamin 23.15. 2-Methyl-pipenziQ 23,17, II16. 3.5-Dimethyi.pyrazolidin 88,18. 

Polyamides with inherent dissymmetry and no asymmetric carbon. Although they do not fall formally in this paragraph, it seems convenient to report here data on polyamides which are chiral by atropoisomerism due to restricted chain rotation in the repeating unit such polymers may assume preferential asymmetric conformations in solution. This could be achieved by polycondensation of either optically active cyclic or biphenyldicarboxylic acids with acyclic and cyclic symmetrical diamines (Scheme XXVI). Thus, optically active (-)-(5 )-2,2 -dinitro-6,6 -dimethylbiphenyl-4,4 -dicarboxylic acids (XXVIa) were chosen as diacid components, a series of phenylene diamines (o, m, p) and cyclic diamines such as piperazine, trans-2,5-dimethylpiperazine and 1,2-pyrazolidine were used in order to main-... 

Yamashita Y, Kobayashi S. Zirconium-catalyzed enantioselective [3-1-2] cycloaddition of hydrazones to olefins leading to optically active pyrazolidine, pyrazoline and 1, 3-diamine derivatives. 7 Am. Chem. Soc. 2004 126 1279-11282. 

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