PREPARATION OF ORGANOALUMINUM COMPOUNDS BY HYDROZIRCONATION-TRANSMETALATION
PREPARATION OF ORGANOALUMINUM COMPOUNDS BY HYDROZIRCONATION-TRANSMETALATION
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DOI：
10.1021/ja00507a017
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发表时间：
1979-01-01
影响因子：
15
通讯作者：
SCHWARTZ, J
中科院分区：
文献类型：
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作者：
CARR, DB;SCHWARTZ, J
通过烯烃或乙炔与 Cp2Zr (H) Cl (Cp= jy-'-CsHs) 的氢锆化产生的有机锆 (IV) 络合物是有机铝化合物的前体。通过化学计量金属转移，可以通过用卤化铝处理将有机配体立体定向地从锆转移至铝。有机二氯化铝可作为温和的烷化剂；它们是通过用酰基氯酰化得到酮的前体（已发现这种酰化对于伯饱和烷基二氯化铝和烯基二氯化铝进行得很好）。乙烯基取代基从Zr到A1的金属转移比烷基取代基发生得更快，并且主要在保留碳构型的情况下进行。假设金属转移的机制，其中过渡态（或中间体）涉及含有桥接烷基（或乙烯基）的过渡金属-主族金属络合物。这一机制与报道的烷基锆配合物的亲电裂解机制类似。酰基二氯化铝是通过 Cp2Zr (Cl)(酰基) 和氯化铝之间的金属转移作用形成的。它们已被证明对酰基的碳和氧都具有亲电试剂反应性。用D 2 O处理酰基二氯化铝产生至少83％-C(0)-D的醛。然而，用乙酰氯处理得到主要产物乙酸α-氯烷基酯（在O处攻击）和作为次要产物的α-二酮（在C处攻击）。
Organozirconium (IV) complexes produced by hydrozirconation of olefins or acetylenes with Cp2Zr (H) Cl (Cp= jy-'-CsHs) are precursors of organoaluminum compounds. By stoichiometric transmetalation, the] organic ligand can be transferred stereospecifically from zirconium to aluminum by treatment with aluminum halides. Organoaluminum dichlorides can act as mild alkylating agents; they are precursors of ketones through acylation with acid chlorides (this acylation has been found to proceed well for primary, saturated alkyl-and alkenylaluminum dichlorides). Transmetalation fromZr to A1occurs faster forvinylic substituents than for alkyl ones and proceeds predominantly with retention of configuration at carbon. A mechanism for transmetalation is postulated in which the transition state (or intermediate) involves a transition metal-main group metal complex containing a bridging alkyl (or vinylic) group. This mechanism is analogous to the one reported for elec-trophilic cleavage of alkylzirconium complexes. Acylaluminum dichlorides have been formed by transmetalation between Cp2Zr (Cl)(acyl) and aluminum chloride. They have been shown to be reactivetoward electrophiles at both the carbon and the oxygen of the acyl group. Treatmentof an acylaluminum dichloride with D2O results in an aldehyde which is at least 83%-C (0)-D. However, treatment with acetyl chloride gives an-chloroalkyl acetate as the major product (attack at O) and an-diketone as a minor product (attack at C).