主链中含有手性铼片段的钯环配合物的合成、结构及反应活性：新型环金属化及催化剂设计策略
Synthesis, structure, and reactivity of palladacycles that contain a chiral rhenium fragment in the backbone: New cyclometalation and catalyst design strategies.
作者信息
Friedlein Florian K, Kromm Klemenz, Hampel Frank, Gladysz J A
机构信息
Institut für Organische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany.
出版信息
Chemistry. 2006 Jul 5;12(20):5267-81. doi: 10.1002/chem.200501540.
The bromocyclopentadienyl complex [(eta5-C5H4Br)Re(CO)3] is converted to racemic [(eta5-C5H4Br)Re(NO)(PPh3)(CH2PPh2)] (1 b) similarly to a published sequence for cyclopentadienyl analogues. Treatment of enantiopure (S)-[(eta5-C5H5)Re(NO)(PPh3)(CH3)] with nBuLi and I2 gives (S)-[(eta5-C5H4I)Re(NO)(PPh3)(CH3)] ((S)-6 c; 84 %), which is converted (Ph3C+ PF6 -, PPh2H, tBuOK) to (S)-[(eta5-C5H4I)Re(NO)(PPh3)(CH2PPh2)] ((S)-1 c). Reactions of 1 b and (S)-1 c with Pd[P(tBu)3]2 yield [{(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(mu-X)}2] (10; X = b, Br, rac/meso, 88 %; c, I, S,S, 22 %). Addition of PPh3 to 10 b gives [(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(PPh3)(Br)] (11 b; 92 %). Reaction of (S)-[(eta5-C5H5)Re(NO)(PPh3)(CH2PPh2)] ((S)-2) and Pd(OAc)(2) (1.5 equiv; toluene, RT) affords the novel Pd3(OAc)4-based palladacycle (S,S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(mu-OAc)2Pd(mu-OAc)2Pd(mu-PPh2CH2)(Ph3P)(ON)Re(eta5-C5H4)] ((S,S)-13; 71-90 %). Addition of LiCl and LiBr yields (S,S)-10 a,b (73 %), and Na(acac-F6) gives (S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(acac-F6)] ((S)-16, 72 %). Reaction of (S,S)-10 b and pyridine affords (S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(NC5H5)(Br)] ((S)-17 b, 72 %); other Lewis bases yield similar adducts. Reaction of (S)-2 and Pd(OAc)2 (0.5 equiv; benzene, 80 degrees C) gives the spiropalladacycle trans-(S,S)-[{(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)}2Pd] (39 %). The crystal structures of (S)-6 c, 11 b, (S,S)- and (R,R)-132 C7H8, (S,S)-10 b, and (S)-17 b aid the preceding assignments. Both 10 b (racemic or S,S) and (S)-16 are excellent catalyst precursors for Suzuki and Heck couplings.
溴环戊二烯基配合物[(η⁵-C₅H₄Br)Re(CO)₃]按照已发表的环戊二烯基类似物的步骤被转化为外消旋的[(η⁵-C₅H₄Br)Re(NO)(PPh₃)(CH₂PPh₂)] (1 b)。用正丁基锂和碘处理对映体纯的(S)-[(η⁵-C₅H₅)Re(NO)(PPh₃)(CH₃)]得到(S)-[(η⁵-C₅H₄I)Re(NO)(PPh₃)(CH₃)] ((S)-6 c；产率84%)，其被转化(三苯基碳正离子六氟磷酸盐、二苯基膦、叔丁醇钾)为(S)-[(η⁵-C₅H₄I)Re(NO)(PPh₃)(CH₂PPh₂)] ((S)-1 c)。1 b和(S)-1 c与Pd[P(tBu)₃]₂反应生成[{(η⁵-C₅H₄)Re(NO)(PPh₃)(μ-CH₂PPh₂)Pd(μ-X)}₂] (10；X = b，Br，外消旋/内消旋，产率88%；X = c，I，S,S，产率22%)。向10 b中加入三苯基膦得到[(η⁵-C₅H₄)Re(NO)(PPh₃)(μ-CH₂PPh₂)Pd(PPh₃)(Br)] (11 b；产率92%)。(S)-[(η⁵-C₅H₅)Re(NO)(PPh₃)(CH₂PPh₂)] ((S)-2)与醋酸钯(1.5当量；甲苯，室温)反应得到新型的基于Pd₃(OAc)₄的钯环(S,S)-[(η⁵-C₅H₄)Re(NO)(PPh₃)(μ-CH₂PPh₂)Pd(μ-OAc)₂Pd(μ-OAc)₂Pd(μ-PPh₂CH₂)(Ph₃P)(ON)Re(η⁵-C₅H₄)] ((S,S)-13；产率71 - 90%)。加入氯化锂和溴化锂得到(S,S)-10 a,b (产率73%)，加入六氟乙酰丙酮钠得到(S)-[(η⁵-C₅H₄)Re(NO)(PPh₃)(μ-CH₂PPh₂)Pd(acac-F₆)] ((S)-16，产率72%)。(S,S)-10 b与吡啶反应得到(S)-[(η⁵-C₅H₄)Re(NO)(PPh₃)(μ-CH₂PPh₂)Pd(NC₅H₅)(Br)] ((S)-17 b，产率72%)；其他路易斯碱也生成类似的加合物。(S)-2与醋酸钯(0.5当量；苯，80℃)反应得到螺环钯环反式-(S,S)-[{(η⁵-C₅H₄)Re(NO)(PPh₃)(μ-CH₂PPh₂)}₂Pd] (产率39%)。(S)-6 c、11 b、(S,S)-和(R,R)-13、2 C₇H₈、(S,S)-10 b以及(S)-17 b的晶体结构有助于上述归属。10 b(外消旋或S,S)和(S)-16都是用于铃木和赫克偶联反应的优秀催化剂前体。
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