A mild and practical procedure for the Wittig olefination, promoted by lithium hydroxide and triphenylbenzyl phosphonium bromide, has been set up for the synthesis of stilbenes and styrenes. The experimental conditions allow aromatic, heteroaromatic, unsaturated and saturated aliphatic aldehydes to give final products in good yields.
A direct synthesis of olefins by reaction of carbonyl compounds with lithio derivatives of 2-[alkyl- or (2′-alkenyl)- or benzyl-sulfonyl]-benzothiazoles.
作者:Jean Bernard Baudin、Georges Hareau、Sylvestre A. Julia、Odile Ruel
DOI:10.1016/s0040-4039(00)92037-9
日期:1991.2
During the title reaction, the lithium alkoxides formed as intermediates undergo an intramolecular addition to the neighboring CN group followed an S to 0 benzothiazole transfer and simultaneous extrustion of sulfur dioxide and ejection of 2(3H)-benzothiazolone anion.
Selenium stabilized carbanions. .alpha.-Lithio selenoxides as reagents for the synthesis of olefins, allyl alcohols, and dienes
作者:Hans J. Reich、Shrenik K. Shah、Flora Chow
DOI:10.1021/ja00516a026
日期:1979.10
Techniques for the preparation of a-lithio selenoxides have been developed. These reagents react cleanly with most aldehydes and ketones to give 0-hydroxy selenoxides, which can be thermolyzed to allyl alcohols or reduced to hI result of the limited acidifying power of the phenylseleno group, and the propensity of selenides to be fragmented upon treatment with powerful metalating agents. The substantially
Gold(I)-Catalyzed Highly Enantioselective [4 + 2]-Annulations of Cyclopentadienes with Nitrosoarenes via Nitroso-Povarov versus Oxidative Nitroso-Povarov Reactions
作者:Prakash D. Jadhav、Jia-Xuan Chen、Rai-Shung Liu
DOI:10.1021/acscatal.0c01293
日期:2020.5.15
gold-catalyzed highlyenantioselective nitroso-Povarov reactions between cyclopentadienes and nitrosoarenes in cold dichloroethane, in which nitrosoarenes serve as 4π-electron donors and cyclopentadienes as 2π-donors. High enantioselectivity has been achieved for substrates over a wide scope. With the same chiral catalyst, nitroso-4-fluorobenzenes in these reactions under DCM/THF/water/air led to oxidative nitroso-Povarov
as zeolites and clays, catalyse the intramolecular hydroxyalkylation (cyclialkylation) of several arylalkyl epoxides in moderate to excellent conversions and selectivities. The use of solid acids in these cyclialkylations provides a cleaner, better alternative to conventional Lewis and Brønsted acids, enabling a more facile workup of reaction mixtures and, in several cases, better selectivities.