Stereoselection at the Steady State in Radical Cyclizations of Acyclic Systems Containing One Radical Acceptor and Two Precursors in a 1,5- Relationship under Pseudo-First-Order Conditions
摘要:
The first example of a successive kinetic resolution of acyclic diastereomeric radical intermediates in a 1,5-relationship under pseudo-first-order conditions is reported. A mechanistic model involves nonselective generation of the radical intermediates followed by different partitioning of these between two different chemical pathways. The "2,5-cis" selectivity in the radical cyclization step arises from transition geometries with the substituents aligned in pseudoequatorial positions.
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。
Two new routes to the C19C26 tetrahydrofuran fragment of the acyl tetronic acid ionophore tetronasin (ICI M139603)
作者:Geert-Jan Boons、Dearg S. Brown、J.Andrew Clase、Ian C. Lennon、Steven V. Ley
DOI:10.1016/s0040-4039(00)76542-7
日期:1994.1
Two highly efficient and complementary synthetic routes to the C19-C26 tetrahydrofuran fragment (2) of the novel acyltetronic acid ionophore antibiotic tetronasin (ICI 139603) (1) are described to provide multigramme quantities of the required product.