35266-82-1Relevant academic research and scientific papers
Base-Mediated O-Arylation of Alcohols and Phenols by Triarylsulfonium Triflates
Ming, Xiao-Xia,Tian, Ze-Yu,Zhang, Cheng-Pan
supporting information, p. 3370 - 3379 (2019/11/03)
A mild and efficient protocol for O-arylation of alcohols and phenols (ROH) by triarylsulfonium triflates was developed under transition-metal-free conditions. Various alcohols, including primary, secondary and tertiary, and phenols bearing either electron-donating or electron-withdrawing groups on the aryl rings were smoothly converted to form the corresponding aromatic ethers in moderate to excellent yields. The reactions were conducted at 50 or 80 °C for 24 h in the presence of a certain base and showed good functional group tolerance. The base-mediated arylation with asymmetric triarylsulfonium salts could selectively transfer the aryl groups of sulfoniums to ROH, depending on their inherent electronic nature. The mechanistic studies revealed that the reaction might proceed through the nucleophilic attack of the in situ formed alkoxy or phenoxy anions at the aromatic carbon atoms of the C?S bonds of triarylsulfonium cations to furnish the target products.
Stereoselective Friedel-Crafts alkylation catalyzed by squalene hopene cyclases
Hammer, Stephan C.,Dominicus, J?rg M.,Syrén, Per-Olof,Nestl, Bettina M.,Hauer, Bernhard
experimental part, p. 7624 - 7629 (2012/09/21)
In organic synthesis the Friedel-Crafts alkylation is of eminent importance, as it is a key reaction in many synthetic routes. A general access to enzymatic Friedel-Crafts alkylations would be very beneficial due to the high selectivity of biocatalysts. We used designed polyprenyl phenyl ethers to specifically address this reaction by using squalene hopene cyclases as catalysts. Polycyclic products with aromatic rings constituting important biological active compounds were obtained. Our results demonstrate that squalene hopene cyclases can be utilized for Friedel-Crafts alkylations and reveal the potential of these enzymes for chiral Bronsted acid catalysis.
Copper(II)-catalyzed ether synthesis from aliphatic alcohols and potassium organotrifluoroborate salts
Quach, Tan D.,Batey, Robert A.
, p. 1381 - 1384 (2007/10/03)
(Matrix presented) A protocol for the copper(II)-catalyzed etherification of aliphatic alcohols under mild and essentially neutral conditions is described. Air- and moisture-stable potassium alkenyl- and aryltrifluoroborate salts undergo cross-coupling with a variety of aliphatic primary and secondary alcohols and phenols, and are tolerant of a range of functional groups. The optimized conditions utilize catalytic copper(II) acetate with 4-(dimethylamino)pyridine as ligand in the presence of 4 A molecular sieves under an atmosphere of oxygen.
Enantioselective biomimetic cyclization of isoprenoids using Lewis acid-assisted chiral Bronsted acids: Abnormal claisen rearrangements and successive cyclizations
Nakamura, Shingo,Ishihara, Kazuaki,Yamamoto, Hisashi
, p. 8131 - 8140 (2007/10/03)
Syntheses of polycyclic isoprenoids have been achieved by several groups; however, no general "biomimetic" method has yet been reported. In this paper we describe the biomimetic cyclization of simple isoprenoids to polycyclic isoprenoids using Lewis acid-assisted chiral Bronsted acids, "chiral LBAs". This is the first example of a proton-induced enantioselective ene cyclization in synthetic chemistry. Geranyl phenyl ethers, o-geranylphenols, and geranylacetone derivatives were directly cyclized at -78 °C in the presence of (R)-binaphthol derivatives and tin tetrachloride. During the cyclization, [1,3] abnormal Claisen rearrangement often took place. The enantioselectivities were up to 90% ee. Compounds bearing a farnesyl group could also be cyclized under the same conditions to give the natural products (-)-Ambrox and (-)-chromazonarol. These chiral LBAs recognize a trisubstituted terminal olefin enantiotopically and generate site-selective carbocations on the substrates. The absolute stereochemistry of the cyclization is discussed with model studies using DFT calculations on the B3LYP/LANL2DZ level.
Geiparvarin analogues. 3. Synthesis and cytostatic activity of 3(2H)- furanone and 4,5-dihydro-3(2H)-furanone congeners of geiparvarin, containing a geraniol-like fragment in the side chain
Baraldi,Manfredini,Simoni,Tabrizi,Balzarini,De Clercq
, p. 1877 - 1882 (2007/10/02)
Continuing our study on the structural features of geiparvarin (1), responsible for cytostatic activity, a series of 4,5-dihydro-3(2H)-furanones 10a-f and of 3(2H)-furanones 11a-f as well as 2'',3''-dihydrogeiparvarin (14) have been designed and synthesiz
