Tandem dienyne ring-closing metathesis of alkynyl silaketals for the formation of bicyclic siloxanes
摘要:
The tandem dienyne ring-closing metathesis of alkynyl silaketals containing two tethered olefins was achieved with second generation Grubbs NHC-ruthenium carbene complex to provide bicyclic siloxanes in good to excellent yield. Silaketals synthesized from homoallylic or bishomoallylic alcohols via base-catalyzed alcoholysis of trialkynylsilanes were well tolerated in the metathesis process and generated ring systems of various sizes. Removal of the silicon tether was achieved through protodesilylation with fluoride to afford stereochemically defined (1E,3Z)-dienes. (c) 2005 Elsevier B.V. All rights preserved.
Hydroxy-Directed Cyclopropanation of Esters: Synthesis of Trisubstituted Cyclopropanols
作者:Dmitry Astashko、Jin Kun Cha、Nagavaram Narsimha Rao、Bibhuti Bhusan Parida
DOI:10.1002/ejoc.201301252
日期:2014.1
The Kulinkovich cyclopropanation of esters with disubstituted homoallylic alcohols is described for the preparation of 1,2,3-trisubstituted cyclopropanols. Central to the successful implementation is the generation in situ of a temporary alkoxy tether between a homoallylic alcohol and an alkoxytitanium species to override unfavorable steric factors.
Highly Stereoselective Synthesis of<i>Z</i>-Homoallylic Alcohols by Kinetic Resolution of Racemic Secondary Allyl Boronates
作者:Celia A. Incerti-Pradillos、Mikhail A. Kabeshov、Andrei V. Malkov
DOI:10.1002/anie.201300709
日期:2013.5.10
α to Z: Racemic α‐chiral allyl boronates, which are readily synthesized from the respective primary allyl halides, undergo a highly efficient kinetic resolution in a face‐ and Z‐selective allylation of aldehydes catalyzed by the chiral Brønsted acid (R)‐TRIP (see scheme; Epin=tetraethylethylene glycol).
Kinetic Resolution of Secondary Allyl Boronates and Their Application in the Synthesis of Homoallylic Amines
作者:Laura Villar、Nikolai V. Orlov、Nikolay S. Kondratyev、Uxue Uria、Jose L. Vicario、Andrei V. Malkov
DOI:10.1002/chem.201804395
日期:2018.11.2
chromatographically‐stable secondary allyl boronates featuring a 1,1,2,2‐tetraethyl‐1,2‐ethanediol fragment (Epin) were obtained by kinetic resolution of their racemic mixtures. The Epin group at boron considerably improved stability of allyl boronates allowing them to be readily isolated by chromatography on silica. The resolved reagents were applied in stereoselective synthesis of homoallylic amines with an internal
Tandem dienyne ring-closing metathesis of alkynyl silaketals for the formation of bicyclic siloxanes
作者:Jonathan B. Grimm、Ryan D. Otte、Daesung Lee
DOI:10.1016/j.jorganchem.2005.04.037
日期:2005.12
The tandem dienyne ring-closing metathesis of alkynyl silaketals containing two tethered olefins was achieved with second generation Grubbs NHC-ruthenium carbene complex to provide bicyclic siloxanes in good to excellent yield. Silaketals synthesized from homoallylic or bishomoallylic alcohols via base-catalyzed alcoholysis of trialkynylsilanes were well tolerated in the metathesis process and generated ring systems of various sizes. Removal of the silicon tether was achieved through protodesilylation with fluoride to afford stereochemically defined (1E,3Z)-dienes. (c) 2005 Elsevier B.V. All rights preserved.