Your wish is my command: Deracemization is a powerful strategy wherein a racemate is converted into a 100 % yield of a single enantiopure product. A new concept in catalyticderacemization is presented, in which a racemate with n stereogenic elements can be selectively converted into each one of 2m (m=number of chiral centers of the product) different enantiopure products, by simple tuning of the reaction
new atom‐economical method for the synthesis of functionalized cyclobutenes has been developed. This versatile sequence hinges upon a unique combination of an elegant photochemical isomerization and a palladium‐catalyzed alkylation, and converts the readily available, “flat” aromatic 2‐pyrone into a variety of functionalized products with exquisite stereoselectivity.
Open sesame: A directsynthesis of functionalised and stereodefined dienes, relying on a domino allylic alkylation/electrocyclic ring‐opening sequence, is reported. This method allows concise access to doubly vinylogous esters. A further systematic study of ring‐opening rates of carbon‐substituted cyclobutenes allowed the design of substrates amenable to sequential pericyclic reactions (see scheme)
A copper-promoted flexible synthesis of cyclobutenes carrying simple alkyl chains, enabling even the most hindered nucleophiles to be employed, has been developed. The versatility of this approach was exemplified by a short total synthesis of ieodomycin D and a straightforward preparation of the southeastern fragment of macrolactin A. The latter features a late-stage, double cyclobutene electrocyclic
已经开发出一种由铜促进的带有简单烷基链的环丁烯的灵活合成,即使是最受阻的亲核试剂也能被使用。这种方法的多功能性体现在碘霉素 D 的短全合成和大环乳素 A 东南片段的直接制备。后者具有后期双环丁烯电环开环,可直接提供定义几何形状的双二烯.
Chemical repercussions of orbital interactions through bond and through space. Effect of remote substituents on the addition of nitrenes to bicyclic olefins
作者:R. Alan Aitken、Ian Gosney、Hugh Farries、Michael H. Palmer、Isobel Simpson、J.I.G. Cadogan、Edward J. Tinley
DOI:10.1016/s0040-4020(01)96535-4
日期:1985.1
form aziridines is offered in terms of orbitalinteractions between the distant groups and the olefinic bond, making the latter remarkably electron deficient as evidenced by UV-photoelectron spectrosoopy. Because of the complexity of the spectra, identification of the Ip associated with the reactive π-centre was made by recourse to ab initio configuration interaction calculations for key members of the