Scope and Limitations of the Scandium-Catalyzed Enantioselective Addition of Chiral Allylboronates to Aldehydes
作者:Dennis G. Hall、Michel Gravel、Hugo Lachance、Xiaosong Lu
DOI:10.1055/s-2004-822359
日期:——
Scandium triflate catalyzes the addition of camphor-derived allyl-, methallyl-, and crotylboronates to aldehydes to provide homoallylic alcohols with excellent diastereo- and enantioselectivity. Aromatic, aliphatic, and propargylic aldehydes can be used successfully in this system. Additional advantages of the camphor-diol allylboronates are their ease of synthesis, their availability in both enantiomeric forms, and their stability towards silica gel chromatography. The usefulness of this methodology is further demonstrated by the gram-scale synthesis of various homoallylic alcohols of high enantiomeric excess and by the concise synthesis of the pheromone (4S)-2-methyloctan-4-ol.
Scandium-Catalyzed Allylboration of Aldehydes as a Practical Method for Highly Diastereo- and Enantioselective Construction of Homoallylic Alcohols
作者:Hugo Lachance、Xiaosong Lu、Michel Gravel、Dennis G. Hall
DOI:10.1021/ja036807j
日期:2003.8.1
A general approach for the allylation of aldehydes using stable, air-tolerant camphor-based chiralallylboronates under Sc(OTf)3 catalysis is described. This practical methodology provides both syn and anti propionate units and other homoallylic alcohols with very high levels of diastereo- and enantioselectivity for several substrates, including functionalized aliphatic aldehydes useful toward the
Stereoselective Synthesis of Spirocyclic Oxindoles via Prins Cyclizations
作者:M. Paola Castaldi、Dawn M. Troast、John A. Porco
DOI:10.1021/ol901201k
日期:2009.8.6
The synthesis of spirocyclic oxindole pyran and oxepene frameworks using highlystereoselective Prins cyclizations of homoallylic and bis-homoallylic alcohols and isatin ketals is described.
Phosphate-Tether-Mediated Ring-Closing Metathesis for the Preparation of Complex 1,3-<i>anti</i>-Diol-Containing Subunits
作者:Rambabu Chegondi、Soma Maitra、Jana L. Markley、Paul R. Hanson
DOI:10.1002/chem.201300913
日期:2013.6.17
phosphate‐tether‐mediated ring‐closing metathesis reactions, which highlight the importance of product ring size and substrate stereochemical compatibility, as well as complexity, is reported. Studies focus primarily on the formation of bicyclo[n.3.1]phosphates, involving the coupling of C2‐symmetric dienediol subunits with a variety of simple, as well as complex, alcohol partners.
报告了一系列非对映选择性、磷酸盐系链介导的闭环复分解反应的例子,它们强调了产物环大小和底物立体化学相容性以及复杂性的重要性。研究主要集中在双环 [ n .3.1] 磷酸酯的形成上,涉及C 2对称二烯二醇亚基与各种简单和复杂的醇伙伴的偶联。
An Intramolecular Diels−Alder Strategy for the Asbestinins: Enantioselective Total Syntheses of 11-Acetoxy-4-deoxyasbestinin D and Asbestinin-12
作者:Michael T. Crimmins、J. Michael Ellis
DOI:10.1021/jo0712695
日期:2008.3.1
[Graphics]The enantioselective total syntheses of 11-acetoxy-4-deoxyasbestinin D and asbestinin-12 have been completed. A glycolate aldol reaction provided a diene useful for ring-closing metathesis to form an oxonene, which was ultimately employed as a template to execute a highly stereoselective intramolecular Diels-Alder cycloaddition, forming the hydroisobenzofuran moiety. The absolute configuration of the asbestinin subclass was confirmed via these synthetic efforts.