A mild and convenient method for the synthesis of 2,2-dihaloketones and gem-dihalolactols has been developed. For the synthesis of 2,2-dihaloketones, alkynes were employed as substrates to react with halogenating agents, Cl2 or ClBr, that were generated in situ from aqueous HCl and NCS or NBS, respectively. On the other hand, gem-dihalolactols could be prepared from alkynol substrates by using the
α-dichloroketones and α-chlorohydrins from various aryl terminal, diaryl internal, and aliphatic terminal alkynes and alkenes, respectively. The commercially available tert-butyl hypochlorite (tBuOCl) was employed as a suitable chlorinating reagent, being accompanied by the less harmful tBuOH as the by-product. In addition, the oxygen atoms in the products came from water rather than molecular oxygen, based on
在此,我们报告了一种无添加剂的方案,用于分别从各种芳基末端、二芳基内部和脂肪族末端炔烃和烯烃轻松合成α,α-二氯酮和α-氯醇。使用市售的次氯酸叔丁酯( t BuOCl)作为合适的氯化剂,并伴随副产物危害较小的t BuOH。此外,根据18 个O 标记实验,产品中的氧原子来自水而不是分子氧。同时,对Z-烯烃和相应的E-烯烃的非对映选择性进行了比较和合理化。通过一组对照实验,提出了可能的机制,即通常以马尔可夫尼科夫加成方式对不饱和 C-C 键进行初始亲电氯化,然后与水进行亲核加成。这项工作简化了在环境条件下使用温和氯源和绿色氧源的氧氯化方法。
Aralkyl carbinols
申请人:UNION CARBIDE CORP
公开号:US02816930A1
公开(公告)日:1957-12-17
Regioselective Dihalohydration Reactions of Propargylic Alcohols: Gold-Catalyzed and Noncatalyzed Reactions
作者:Jarryl M. D'Oyley、Abil E. Aliev、Tom D. Sheppard
DOI:10.1002/anie.201405348
日期:2014.9.26
The regioselective conversion of propargylicalcohols into previously unreported α,α‐diiodo‐β‐hydroxyketones was achieved by treatment with N‐iodosuccinimide in the presence of a gold catalyst. The corresponding α,α‐dichloro‐β‐hydroxyketones were obtained by treatment with trichloroisocyanuric acid in the absence of a catalyst. The latter reaction can be extended to other alkynols. These transformations
An electrochemical oxydihalogenation of alkynes has been developed for the first time. Using this sustainable protocol, a variety of α,α-dihaloketones can be prepared with readily available CHCl3, CH2Cl2, ClCH2CH2Cl, and CH2Br2 as the halogen source under electrochemical conditions at room temperature.