Folding of aromatic oligoimides of trans-1,2-diaminocyclohexaneElectronic supplementary information (ESI) available: CD spectra and experimental details. See http://www.rsc.org/suppdata/cc/b1/b110446b/
Chiral oligomeric diimides prepared from pyromellitic dianhydride, (R,R)-1,2-diaminocyclohexane and phthalic anhydride fold into M or P helical conformers; trimer 1 folds into the P conformer in the crystal but the M conformer dominates in solution; longer chain oligomers 2 and 3 form preferentially P conformers in solution, as a result of intermolecular interactions.
1,2‐Diamine‐Derived (thio)Phosphoramide Organocatalysts in Asymmetric Michael Additions
作者:Viktória Kozma、Ferenc Fülöp、György Szőllősi
DOI:10.1002/adsc.202000335
日期:2020.6.15
Phosphoramides and thiophosphoramides were prepared from optically pure C2‐symmetric 1,2‐diamines and were used as chiral organocatalysts in the asymmetric Michael additions of aldehydes and ketones to N ‐substituted maleimides. The 1,2‐diphenylethane‐1,2‐diamine derived thiophosphoramide, which could be prepared in good yield in a one‐step procedure, was found to be more active and selective catalyst
Silicon Amine Reagents for the Photocatalytic Synthesis of Piperazines from Aldehydes and Ketones
作者:Sheng-Ying Hsieh、Jeffrey W. Bode
DOI:10.1021/acs.orglett.6b00722
日期:2016.5.6
Silicon amine protocol (SLAP) reagents for photocatalytic cross-coupling with aldehydes and ketones to form N-unprotected piperazines have been developed. This blue light promoted process tolerates a wide range of heteroaromatic, aromatic, and aliphatic aldehydes and structurally and stereochemically complex SLAP reagents. It provides a tin-free alternative to SnAP (tin amine protocol) reagents for
Thiourea-Catalyzed Highly Enantio- and Diastereoselective Additions of Oxindoles to Nitroolefins: Application to the Formal Synthesis of (+)-Physostigmine
作者:Tommy Bui、Salahuddin Syed、Carlos F. Barbas
DOI:10.1021/ja903520c
日期:2009.7.1
molecules. Most catalytic methods for the asymmetric syntheses of these compounds rely heavily on the use of transition-metal catalysts. In contrast, alternative catalytic procedures involving organocatalysis are scarce. Herein we disclose a conceptually novel organocatalytic approach to the syntheses of these materials using thiourea-catalyzed asymmetric 1,4-additions of oxindole derivatives to nitroolefins
Enantioselective Synthesis of 4<i>H</i>-Pyrans Through Organocatalytic Asymmetric Formal [3+3] Cycloadditions of 2-(1-Alkynyl)-2-alken-1-ones with β-Keto Esters
4H‐Pyran units are frequently present in molecules with significant biological and pharmaceutical activities. Herein, we present the first enantioselective formal [3+3] cycloaddition between 2‐(1‐alkynyl)‐2‐alken‐1‐ones and β‐keto esters catalyzed by a cyclohexyldiamine‐based thiourea‐tertiary amine bifunctional catalyst. Under the mild and eco‐friendly conditions, a wide range of polysubstituted 4H‐pyrans