Efficient construction of organic molecular skeleton by using spiro-type catalysts

我们开发了一种独特的手性配体SPRIX(1)，在刚性螺旋骨架上具有异恶唑啉配位位点。SPRIX对Pd（II）的良好亲和力及其在酸性和氧化条件下的高稳定性促使我们探索新的不对称Pd催化。在此，我们开发了一个由Pd- sprix配合物催化的炔基环己二烯酮2的对映选择性氧化顺序反应，该反应涉及Pd烯酸酯中间体的不寻常的羧基化。在氧气氛（1atm）下，在acoh -甲苯的9:1混合物中，在10mol %的Pd(OAc)2和15mol %的（M，S，S）-i-Pr-SPRIX （1d）的存在下，在60℃下反应顺利进行，产物3的产率高达71%。我们还开发了一种新的对映选择性Pd(II)/Pd（IV）催化剂，利用1,1-二苯基丁-3-烯-1-醇(4)，得到光学活性4-乙酰氧基-5,5-二苯基四氢呋喃(5)，收率为92%，ee为90%。

We have developed a unique chiral ligand SPRIX (1), possessing isoxazoline coordination sites on a rigid spiro backbone. The good affinity of SPRIX towards Pd(II) and its high stability under acidic and oxidative conditions encouraged us to explore new asymmetric Pd catalysis.Herein, we have developed an enantioselective oxidative sequential reaction of alkynyl cyclohexadienones 2 catalyzed by Pd-SPRIX complex, which involves an unusual carboxylation of Pd enolate intermediate. The reaction of 2 in the presence of 10 mol % of Pd(OAc)2 and 15 mol % of (M,S,S)-i-Pr-SPRIX (1d) under an oxygen atmosphere (1 atm) in a 9:1 mixture of AcOH-toluene at 60 °C proceeded smoothly to give product 3 in good yields with up to 71% ee. We have also developed a novel enantioselective Pd(II)/Pd(IV) catalysis of alkenyl alcohols utilizing 1,1-diphenylbut-3-en-1-ol (4), leading to optically active 4-acetoxy-5,5-diphenyltetrahydrofuran (5) in 92% yield with 90% ee.