Organocatalysts hydrazine derivatives

Lee and co-workers reported camphor sulfonyl hydrazines 54 as organocatalysts in enantioselective Diels-Alder reactions of cyclopentadiene and a,[L-unsaturated aldehydes, Scheme 3.21 [34], On the other hand, a similar Diels-Alder cycloaddition reactions with camphor-derived sulfonylhydrazines and HC10 in MeNO were also developed by Langlois, et al. [35]. 

In 2008, Suzuki and colleagues reported the use of derivatives of hydrazine as organocatalysts for the Biginelli reaction [50]. Among the catalysts employed, CAT-39 (Table 8) gave better yields with shorter reaction times. CAT-39 gave the desired compoxmds with good yields (70-97%) when isopropyl icohol or DMSO was used as the solvent. 

Regarding the importance of iminium ion formation and geometry in organo-catalytic Diels-Alder reactions, Zhang and coworkers designed and developed a new class of bipyrrolidines 24 as efficient organocatalysts that can form di-iminium intermediates F with a, J-unsaturated aldehydes (14). The predominant exoproducts were obtained with excellent enantioselectivities (Scheme 38.8). Recently, the Suzuki group reported a class of diamine catalysts (25) derived from hydrazines for this reaction to afford products 4 with a preference for the endo isomer (Scheme 38.8) [15],... 

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