Boc-hydrazine

A novel synthesis of aza-/Mactams (Scheme 7.14) from the adducts of the reactions with N-Boc hydrazines 103 was recently reported by Naskar [53]. Thus, direct cyclization of 106 [52] with DIC gave 107, while participation in the Ugi reaction upon the addition of an aldehyde 109 and an isocyanide 110 gave more substituted derivatives 111 [53]. 

More recently, Armstrong et al. reported the use of the diethylketomalonate-derived oxaziridine 77 for the amination of primary amines affording the A -BOC hydrazines in good to excellent yields <20050L713>. This method allows a one-pot synthesis of pyrazoles from primary amines as shown in Scheme 2. 

N-Amination. At low temperatures amines are transformed into N-Boc hydrazines by iV-(t-butoxycarbonyl)-3-trichloromethyloxaziridine. This reagent is superior to the 3-aryl analogs because by-product from the reaction is chloral which is water soluble and much more readily removed. 

A different way was used to build the J -amino substituted benz-isothiazolone nucleus from chlorocarbonylphenylsulfenylchlorides (333) Method S) which, on reaction with hf-Boc-hydrazine in pyridine and... 

Diones and 1,3-dihalides can also be utilized as substrates for azide reagents in the preparation of pyrazoles. Primary aliphatic and aromatic amines 13 underwent electrophilic amination with oxaziridine 14 to give the corresponding A-Boc hydrazines which reacted further... 

In another variant, A-Boc-hydrazine (i-BuOCONHNH2) is coupled with an aryl halide via the carbamate nitrogen the subsequent Fischer sequence can be conducted in the same pot after addition of acid, with loss of the Boc group. ° Hydroamination of alkynes via various protocols ° also produces arylhydrazones, ready for the Fischer process. 

Coupling of aryl halides and trifluoroacetamide occurred at 45-75 °C catalyzed by CuI/DMEDA (Lll), followed by in situ hydrolysis to provide the corresponding primary arylamines (entry 2) [32]. The Cul/l,10-phen (L13) catalytic system was found to be able to promote the selective coupling of N-Boc hydrazine [33] (entry 3) and the coupling of N- and O- functionalized hydroxylamines with aryl iodides (entry 4) [34]. Hosseinzadeh and coworkers reported the coupling reaction of aryl iodides with amides catalyzed by CuI/l,10-Phen (L13) by using KF/AI2O3 as the... 

Acyl-lH-pyrazoles 63 can be obtained via three-component reaction starting from glyoxyHc acids 59, phenyl acetylene (5j), and Boc-hydrazine (20b) applying the activation protocol. Subsequent cleavage of the... 

Shibata and coworkers [135] described the asymmetric phase-transfer catalytic synthesis of trifluoromethyl-substituted 2-isoxazolines 100 by an enantioselective conjugate addition of hydroxylamine to trifluoromethylated enones 99 and subsequent intramolecular formation of the imine, whereas Briere et al. [136] developed a facile method for the straightforward enantioselective synthesis of 3,5-diaryl pyrazoHnes 102 by phase-transfer-catalyzed conjugate addition of N-Boc-hydrazine... 

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