The Supersilyl Group as a Carboxylic Acid Protecting Group: Application to Highly Stereoselective Aldol and Mannich Reactions
作者:Jiajing Tan、Matsujiro Akakura、Hisashi Yamamoto
DOI:10.1002/anie.201300102
日期:2013.7.8
Silyl superpowers: The supersilylgroup was investigated as a superior carboxylicacidprotectinggroup. Supersilyl esters were also utilized as stable carboxylicacid synthetic equivalents in highlystereoselectivealdol and Mannichreactions (see scheme). The value of this method lies in easy photodeprotection and in the rapid synthesis of polyketide subunits.
Asymmetric aziridine synthesis by aza-Darzens reaction of N-diphenylphosphinylimines with chiral enolates. Part 1: Formation of cis-aziridines
作者:J.B. Sweeney、Alex A. Cantrill、Andrew B. McLaren、Smita Thobhani
DOI:10.1016/j.tet.2006.01.068
日期:2006.4
The aza-Darzens (‘ADZ’) reactions of N-diphenylphosphinyl (‘N-Dpp’) imines with chiral enolates derived from oxazolidinones and camphorsultam have been studied. Whilst oxazolidinone enolates reacted poorly in terms of aziridination, the use of the chiral enolate derived from both antipodes of N-bromoacetyl 2,10-camphorsultam, 2R-(5) and 2S-(5), with N-diphenylphosphinyl aryl and tert-butylimines proceeded
Tandem Processes Identified from Reaction Screening: Nucleophilic Addition to Aryl <i>N</i>-Phosphinylimines Employing La(III)-TFAA Activation
作者:Hidenori Kinoshita、Oscar J. Ingham、Winnie W. Ong、Aaron B. Beeler、John A. Porco
DOI:10.1021/ja100346w
日期:2010.5.12
Reaction screening of nucleophilic reaction partners for addition to N-diphenylphosphinylimines employing lanthanum(III) triflate as a catalyst and trifluoroaceticanhydride (TFAA) as an activator is reported. A number of tandem processes leading to novel chemotypes including aza-Prins/intramolecular Friedel-Crafts annulations have been identified, and both reaction scope and mechanism further investigated
Lewis Acid Catalyzed Borotropic Shifts in the Design of Diastereo- and Enantioselective γ-Additions of Allylboron Moieties to Aldimines
作者:Farid W. van der Mei、Hiroshi Miyamoto、Daniel L. Silverio、Amir H. Hoveyda
DOI:10.1002/anie.201600546
日期:2016.4.4
Catalytic allylboron additions to aldimines are presented for which small amounts of Zn(OMe)2 serve as the co‐catalyst to accelerate allyl exchange and 1,3‐borotropicshift processes. Low‐yielding and moderately α‐ and diastereoselective reactions are thus turned into highly efficient γ‐, diastereo‐, and enantioselective transformations that exhibit considerable scope.
The use of binaphthophosphepine 1a as a catalyst for the [3+2] cyclisation between allenoates or 2-butynoates andimines was investigated. The effects of the imine protecting group on both the catalytic activity and enantioselectivity were determined by comparing the behaviour of N-tosyl- and N-DPP-imines. The N-DPP-imines displayed lower reactivity, but afforded the desired pyrrolines in higher enantiomeric