Exploration of the interrupted Fischer indolization reaction
作者:Alex W. Schammel、Ben W. Boal、Liansuo Zu、Tehetena Mesganaw、Neil K. Garg
DOI:10.1016/j.tet.2010.02.050
日期:2010.6
molecules has been developed. The strategy involves the condensation of hydrazines with latent aldehydes to ultimately deliver indoline-containing products by way of an interrupted Fischer indolization sequence. The method is convergent, mild, operationally simple, broad in scope, and can be used to access enantioenriched products. In addition, our approach is amenable to the synthesis of furoindoline
已经开发了一种收敛方法来访问存在于大量生物活性分子中的稠合二氢吲哚环系统。该策略涉及肼与潜在醛的缩合,以通过中断的 Fischer 吲哚化序列最终提供含二氢吲哚的产物。该方法收敛、温和、操作简单、适用范围广,可用于获得对映体富集的产品。此外,我们的方法适用于呋喃二氢吲哚和吡咯烷二氢吲哚天然产物的合成,如 physovenine 和 debromoflustramine B 的简洁正式全合成所证明的那样。 该策略可能会合成更复杂的目标,如公社生物碱。
Synthesis of 4,4′-Disubstituted Azepines via Ring-Closing Metathesis Reaction and Asymmetric Arylation of Lactones
The syntheses of the title compounds were accomplished via an original sequence of reactions including the ring-closing metathesis of Ï-dienes by using the second-generation Grubbs’ catalyst. The chiral diene precursors are available in racemic or optically enriched form from the corresponding α,α′-disubstituted lactones derivatives
Monosubstituted γ-lactols 1a−1c, 3a−3c and 4a−4c, as well as disubstituted γ-lactol 5 and the γ-hydroxy-substituted γ-lactone 6, were transformed into disubstituted tetrahydrofuran derivatives by treatment with allyl- and propargylsilanes in the presence of Lewis acids. The diastereoselectivities were moderate to excellent and are interpreted by application of the Felkin−Anh model to cyclic oxocarbenium
Formal [4 + 1]- and [5 + 1]-Annulation by an S<sub>N</sub>2–Conjugate Addition Sequence: Stereoselective Synthesis of Highly Substituted Carbocycles
作者:Benny Meng Kiat Tong、Hui Chen、Sin Yee Chong、Yi Li Heng、Shunsuke Chiba
DOI:10.1021/ol301044e
日期:2012.6.1
6-bromo-2-hexenoates and 7-bromo-2-heptenoate with active methylene compounds deliver highly substituted cyclopentane and cyclohexane derivatives, respectively via a sequence of SN2–conjugate addition reactions (formal [4 + 1]- and [5 + 1]-annulation) in a diastereoselective manner.
K 2 CO 3介导的6-溴-2-庚酸和7-溴-2-庚酸与活性亚甲基化合物的反应分别通过一系列S N 2-共轭加成反应(分别为[ 4 + 1]-和[5 +1]-环形)以非对映选择性的方式进行。
Lewis Acid-Promoted Reactions of γ-Lactols with Silyl Enol Ethers — Stereoselective Formation of Functionalized Tetrahydrofuran Derivatives
disubstituted γ-lactol 1e were converted into tetrahydrofuran derivatives by reaction with typical silylenolethers in the presence of Lewis acids. Although the most suitable Lewis acid appears to be zinc chloride, BF3·Et2O or diethylaluminium chloride are also suitable under appropriate conditions. The stereoselectivities of these substitution reactions are similar to those observed with other silylated nucleophiles;