A facile and efficient ZrCl 4 catalyzed conversion of aldehydes to geminal-diacetates and dipivalates and their cleavage
摘要:
A novel, mild and efficient method has been developed for the preparation of geminal-diacetates and dipivalates in high yields through a reaction of aldehydes with acetic anhydride or pivalic anhydride using Zirconium (W) chloride as a catalyst under solvent free conditions. Regeneration of aldehydes from the acylals was also achieved using the same catalyst in CH3OH. (C) 2003 Elsevier Ltd. All rights reserved.
Transition‐Metal‐Free Synthesis of Polyfunctional Triarylmethanes and 1,1‐Diarylalkanes by Sequential Cross‐Coupling of Benzal Diacetates with Organozinc Reagents
A variety of functionalized triarylmethane and 1,1‐diarylalkane derivatives were prepared via a transition‐metal‐free, one‐pot and two‐step procedure, involving the reaction of various benzal diacetates with organozincreagents. A sequential cross‐coupling is enabled by changing the solvent from THF to toluene, and a two‐step SN1‐type mechanism was proposed and evidenced by experimental studies. The
通过无过渡金属的一锅两步程序制备了各种官能化三芳基甲烷和1,1-二芳基烷烃衍生物,其中包括各种二乙酸苯亚缩酯与有机锌试剂的反应。通过将溶剂从 THF 更改为甲苯,可以实现顺序交叉偶联,并提出了两步 S N 1 型机理,并通过实验研究证明了这一点。该方法的合成效用通过几种生物学相关分子的合成得到进一步证明,例如抗结核剂、抗乳腺癌剂、鞘氨醇-1-磷酸(S1P)受体调节剂的前体和FLAP抑制剂。
Cerium(IV) Triflate‐Catalyzed Selective <i>Gem</i>‐diacetylation of Aldehydes with Acetic Anhydride
作者:J. W. John Bosco、Anil K. Saikia
DOI:10.1080/00397910701649106
日期:2007.12.1
Abstract It has been observed that a catalytic amount (0.1 mol%) of cerium(IV) triflate afforded geminal diacetates from aldehydes with acetic anhydride in toluene at ambient temperature. Ketones are not affected under these reaction conditions. The reaction is rapid and mild with good to high yields.
an efficient one-pot, two-step procedure for the modular synthesis of α-difunctionalized alkynes and trisubstituted allenes by sequential cross-coupling of benzal gem-diacetates with organozinc or -copper reagents in the absence of external transition metals. The intermediacy of propargylic acetates enables the divergent and selective synthesis of these valuable products. This method features its readily
Layered zirconium sulfophenyl phosphonate was found to be an efficient heterogeneous catalyst for the preparation and deprotection of 1,1-diacetates. (C) 2002 Elsevier Science Ltd. All rights reserved.