Highly enantioselective synthesis of (+)- and (−)-perfluoroalkyl(aryl) homoallyl alcohols
摘要:
Asymmetric allylboration of perfluoroaldehydes and fluorine substituted aromatic aldehydes with (d)Ipc(2)BAll and 2-Icr(2)BAll has been investigated. Both enantiomers of the fluorinated homoallyl alcohols were obtained in high yields and excellent enantiopurity (95-99% eel. (C) 2001 Elsevier Science Ltd. All rights reserved.
Synthetically amenable amide derivatives of tosylated-amino acids as organocatalysts for enantioselective allylation of aldehydes: computational rationale for enantioselectivity
作者:Debashis Ghosh、Debashis Sahu、S. Saravanan、Sayed H. R. Abdi、Bishwajit Ganguly、Noor-ul H. Khan、Rukhsana I. Kureshy、Hari C. Bajaj
DOI:10.1039/c3ob27513b
日期:——
A phenylalanine derived chiral amide is developed that serves as an effective organocatalyst for the reaction of allyltrichlorosilane with aryl, hetero-aryl and α,β-unsaturated aldehydes to afford the desired homoallylic alcohols in good yield (up to 90%) and high enantioselectivity (up to 99%). The experimental results and DFT calculations suggest that para substituted aromatic aldehydes as substrate show higher ee in the product than their ortho/meta counterparts. The 1H and 13C NMR spectra study corroborated the calculated results. The chiral organocatalyst can be easily synthesized from optically pure phenylalanine in two simple steps with 90% overall yield.
A series of structurally simplepyridineN-oxides have readily been assembled from inexpensive amino acids and tested as organocatalysts in the allylation of aldehydes with allyl(trichloro)silane to afford homoallylic alcohols. (S)-Proline-based catalysts afforded the products derived from aromatic aldehydes in fair to good yields and in up to 84% enantiomeric excess (ee). The allylation of heteroaromatic
Oxazoline derivatives tagged with tosylated amino acids as recyclable organocatalysts for enantioselective allylation of aldehydes
作者:Debashis Ghosh、Arghya Sadhukhan、Nabin Ch. Maity、Sayed H. R. Abdi、Noor-ul H. Khan、Rukhsana I. Kureshy、Hari C. Bajaj
DOI:10.1039/c3ra47424k
日期:——
of amino acid-based oxazoline compounds have been prepared and successfully applied to the enantioselective allylation reaction of aldehydes. The fine-tuning of the structure of the oxazolines led to (S,S)-4 as an efficient organocatalyst which gave homoallyl alcohols in good yield (up to 90%) and excellent ee (up to 99%) for a wide range of substrates including aromatic, hetero-aromatic and α,β-unsaturated
The invention relates to compounds of formula I:
and pharmaceutically acceptable salts thereof wherein A, X, R
1
, R
4
and n are as defined herein. In addition, the present invention relates to methods of manufacturing and methods of using the compounds of formula I as well as pharmaceutical compositions containing such compounds. The compounds may be useful in treating diseases and conditions mediated by TRPA1, such as pain.
Chiral sulfoxides as activators of allyl trichlorosilanes in the stereoselective allylation of aldehydes
作者:Vincenzo De Sio、Antonio Massa、Arrigo Scettri
DOI:10.1039/c002988b
日期:——
Chiral aryl methyl sulfoxides proved to be efficient activators in the asymmetric allylation of aldehydes with allyl trichlorosilanes. High enantioselectivity was found in the case of electron-poor aldehydes. The high levels of diastereoselectivity and the detection of nonlinear effects have allowed the elucidation of some mechanistic aspects of the reaction.