Synthesis and Characterization of R₂PNP(ⁱBuNCH₂CH₂)₃N: A New Bulky Electron-Rich Phosphine for Efficient Pd-Assisted Suzuki−Miyaura Cross-Coupling Reactions

Pro-azaphosphatrane 1a [P(iBuNCH2CH2)3N] reacts with iodine under mild conditions to give [IP(iBuNCH2CH2)3N]I in excellent yield, which on subsequent reaction with ammonia followed by deprotonation with KOtBu provided HNP(iBuNCH2CH2)3N (3a) in quantitative yield. Reaction of 3a with R‘2PCl afforded sterically bulky electron-rich phosphines of the type R‘2PNP(iBuNCH2CH2)3N (4) [R‘ = Ph (4a), iPr (4b), tBu (4c)]. The Pd(OAc)2/4c catalyst system was particularly efficient for the coupling of arylboronic acids with aryl bromides as well as aryl chlorides to give biaryls in excellent yields.前氮杂磷杂三环烷（Pro-azaphosphatrane）1a [P(iBuNCH2CH2)3N] 在温和条件下与碘反应，以优异收率得到[IP(iBuNCH2CH2)3N]I；随后该产物与氨发生反应，再经叔丁醇钾（KOtBu）脱质子，以定量收率得到HN=P(iBuNCH2CH2)3N（3a）。 3a与R'2PCl反应，可得到类型为R'2PN=P(iBuNCH2CH2)3N（4）的位阻型富电子膦配体，其中R'分别为苯基（Ph，4a）、异丙基（iPr，4b）与叔丁基（tBu，4c）。 Pd(OAc)2/4c催化体系对芳基硼酸与芳基溴化物、芳基氯化物的偶联反应尤为高效，可优异收率获得联芳烃产物。