Palladium‐catalyzed cascade CH alkenylation and arylation provides convenient access to polycyclic aromatic compounds. Treatment of 3‐bromoaniline derivatives bearing a bromocinnamyl group on the nitrogen atom with a catalytic amount of [Pd(OAc)2] and PCy3⋅HBF4 in the presence of Cs2CO3 in dioxane affords naphthalene‐fused indole derivatives in good yields. This double cyclization reaction is also
钯催化的级联CH烯基化和芳基化提供了多环芳族化合物的便捷通道。3-溴苯胺衍生物支承在氮原子上的bromocinnamyl组[将Pd(OAc)催化量的治疗2 ]和PCY 3 ⋅HBF 4中Cs的存在2 CO 3在良好的二恶烷,得到萘稠合的吲哚衍生物产量。该双环化反应也适用于杂环底物,通过杂环C产生含杂芳环的稠合吲哚,如二苯并呋喃,二苯并噻吩,咔唑,吲哚或苯并呋喃。盐基化。当使用2,6-未取代的苯胺衍生物时,首个CH芳基化反应优先在苯胺环的受阻位置进行。
α-Hypervalent Iodine Functionalized Phosphonium and Arsonium Ylides and Their Tandem Reaction as Umpolung Reagents
作者:Zhizhen Huang、Xiaochun Yu、Xian Huang
DOI:10.1021/jo026077i
日期:2002.11.1
iodine functionalized phosphonium and arsonium ylides 2 can be used as umpolung ylides to react with nucleophiles to give alpha-heteroatom substituted ylides 4 in good yields. The nucleophilic substitution-Wittig tandem reaction of 2 can occur smoothly to provide an efficient method for the synthesis of (Z)-alpha-halo-alpha,beta-unsaturated enoates or enones 6, stereoselectively.
A Highly Stereoselective Synthesis of (E)-α-Bromoacrylates
作者:Keiko Tago、Hiroshi Kogen
DOI:10.1016/s0040-4020(00)00811-5
日期:2000.11
Novel reagent, methyl bis(2,2,2-trifluoroethoxy)bromophosphonoacetate (5a), was designed and prepared in order to efficiently synthesize (E)-α-bromoacrylates 7, from which widely useful precursors for various C–C bond formations were prepared. Horner–Wadsworth–Emmons (HWE) reaction of various aldehydes with 5a in the presence of t-BuOK and 18-C-6 gave corresponding (E)-α-bromoacrylate derivatives with