Synthetic and mechanistic studies on Pd(0)-catalyzed diamination of conjugated dienes.
Various dienes and a triene can be regioselectively diaminated at the internal double bond with good yields and high diastereoselectivity using di-tert-butyldiaziridinone (5) as the nitrogen source and Pd(PPh(3))(4) (1-10 mol %) as the catalyst. Kinetic studies with (1)H NMR spectroscopy show that the diamination is first-order in total Pd catalyst and inverse first-order in PPh(3). For reactive dienes, such as 1-methoxybutadiene (6g) and alkyl 1,3-butadienes (6a, 6j), the diamination is first-order in di-tert-butyldiaziridinone (5) and zero-order in the olefin. For olefins with relatively low reactivity, such as (E)-1-phenylbutadiene (6b) and (3E,5E)-1,3,5-decatriene (6i), similar diamination rates were observed when 3.5 equiv of olefins were used. Pd(PPh(3))(2) is likely to be the active species for the insertion of Pd(0) into the N-N bond of di-tert-butyldiaziridinone (5) to form a four-membered Pd(II) complex (A), which can be detected by NMR spectroscopy. The olefin complex (B), formed from intermediate A via ligand exchange between the olefin substrate and the PPh(3), undergoes migratory insertion and reductive elimination to give the diamination product and regenerate the Pd(0) catalyst.
Zhao
Baoguo
B
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
Du
Haifeng
H
Cui
Sunliang
S
Shi
Yian
Y
D000466:Alkadienes / Q000737:chemistry*; D000586:Amination; D001388:Aziridines / Q000737:chemistry; D002384:Catalysis; D003959:Diamines / Q000138:chemical synthesis*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009943:Organophosphorus Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*
D000466:Alkadienes; D001388:Aziridines; D003959:Diamines; D009943:Organophosphorus Compounds; C527442:di-tert-butyldiaziridinone; D010165:Palladium