β-Oxidation of Ynamides into N,O-Acetals by mCPBA: Application in Enantioselective Intermolecular Transacetalization
摘要:
Oxidation of ynamides by mCPBA led to beta-oxygenation and resulted in formation of carbonyl compounds with alpha-N,O-acetal functionality. These N,O-acetals are formed in high yields and can be stored indefinitely at room temperature. Yet, they can be activated by a chiral Bronsted acid and underwent an enantioselective transacetalization into a alpha-N,O-acetal. Subsequent diastereoselective transformations occurred with exceptional selectivity according to Felkin-Anh model.
Regiocontrolled Palladium-Catalyzed Arylative Cyclizations of Alkynols
作者:Daishi Fujino、Hideki Yorimitsu、Atsuhiro Osuka
DOI:10.1021/ja5029028
日期:2014.4.30
Tuning the reactivity of arylpalladium intermediates enables control of catalyticarylative 5-exo and 6-endo cyclizations of alkynols. The two modes of cyclizations represent a rare example of controllable, regioselective difunctionalization of alkynes. The cyclizations are useful in offering a divergent synthesis of oxygen-containing heterocycles, which is of synthetic use for further derivatization
indole‐based biaryls with bromoalkyl alkynes by using palladium/norbornene (Pd/NBE) cooperative catalysis. This reaction is realized through a sequence of Catellani‐type C−H alkylation, alkyneinsertion, and indole dearomatization, by forming twoC(sp2)−C(sp3) and one C(sp2)−C(sp2) bonds in a single chemical operation, thus providing a diverse range of pentacyclic molecules, containing a spiroindolenine fragment