Cross-coupling reaction of organosilicon nucleophiles
申请人:——
公开号:US20020183516A1
公开(公告)日:2002-12-05
Improved methods for generating a —C—C— bond by cross-coupling of a transferable group with an acceptor group. The transferable group is a substituent of an organosilicon nucleophile and the acceptor group is provided as an organic electrophile. The reaction is catalyzed by a Group 10 transition metal complex (e.g., Ni, Pt or Pd), particularly by a palladium complex. Certain methods of this invention use improved organosilicon nucleophiles which are readily prepared, can give high product yields and exhibit high stereo selectivity. Methods of this invention employ activating ions such as halides, hydroxide, hydride and silyloxides. In specific embodiments, organosilicon nucleophilic reagents of this invention include siloxanes, particularly cyclic siloxanes. The combination of the cross-coupling reactions of this invention with ring-closing metathesis, hydrosilylation and intramolecular hydrosilylation reactions provide useful synthetic strategies that have wide application.
NOBF4 underbasic or even almost neutral reaction conditions. Acid-sensitive functional groups are tolerated under the developed basicconditions. For the substrates having poor reactivity, almost neutralconditions (using pyridine equimolar to NOBF4) are suitable for better yields. Furoxans (1,2,5-oxadiazole 2-oxides) can be synthesized from the corresponding styrenes using NOBF4 underbasic or even
corresponding styrenes usingnitrosoniumtetrafluoroborate as the nitrosation reagent in pyridine (basic media) or dichloromethane (neutral media). Acid‐sensitive functional groups were tolerated under these conditions. The probable reaction mechanism was elucidated. The experimental results support an ionic reaction pathway in contrast to the conventional acidic conditions with a radical mechanism.
Transition-Metal-Free and Chemoselective NaO<sup><i>t</i></sup>Bu–O<sub>2</sub>-Mediated Oxidative Cleavage Reactions of <i>vic</i>-1,2-Diols to Carboxylic Acids and Mechanistic Insight into the Reaction Pathways
作者:Sun Min Kim、Dong Wan Kim、Jung Woon Yang
DOI:10.1021/ol501012f
日期:2014.6.6
method for efficient oxidativecleavage of vic-1,2-diols using a NaOtBu–O2 system resulted in the formation of carboxylic acids in high yields. The present protocol is an eco-friendly alternative to a conventional transition-metal-based method. This new strategy allows large-scale production with nonchromatographic purification while also suppressing competitive reactionpathway such as benzilic acid
一种使用NaO t Bu–O 2系统对vic -1,2-二醇进行有效氧化裂解的方法,可高产率地形成羧酸。本协议是传统的基于过渡金属的方法的环保替代。这种新策略可以通过非色谱纯化进行大规模生产,同时还可以抑制竞争性反应途径,例如苯甲酸重排。