Chiral tertiary 2-furyl alcohols: diversified key intermediates to bioactive compounds. Their enantioselective synthesis via (2-furyl) aluminium addition to ketones catalyzed by a titanium catalyst of (S)-BINOL

Novel asymmetric 2-furyl additions of (2-furyl)AlEt(2)(THF) to aromatic ketones and one alpha,beta-unsaturated ketone catalyzed by a titanium catalyst of 10-20 mol% (S)-BINOL are reported to furnish tertiary furyl alcohols in good to excellent enantioselectivities of 87-93% ee

Synthesis, characterization, and structures of arylaluminum reagents and asymmetric arylation of aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol

A series of phenylaluminum reagents AlPh(x)Et(3-x)(L) (x = 1-3) containing adduct ligand L [Et(2)O, THF, OPPh(3), or 4-dimethylaminopyridine (DMAP)] were synthesized and characterized. NMR studies showed that AlPh(x)Et(3-x)(L) (x = 1 or 2) exists as an equilibrium Mixture of 3-4 species in Solution. Solid-state structures of the phenylaluminum In reagents reveal a distorted tetrahedral geometry. Asymmetric additions of phenylaluminum to 2-chlorobenzaldehyde were examined employing a titanium(IV) complex [TiL*(OPr(2)(i)](2) 10 (H(2)L* = (1R,2S)-2-(p-tolylsulfonylamino)-1,3-diphenyl-1-propanol) as a catalyst precursor. It was found that the adduct ligand L had a strong influence oil the reactivity and the enantioselectivity in asymmetric phenyl additions to aldehydes. The phenylaluminum reagents with OPPh(3) or DMAP were unreactive toward aldehydes, and AlPh(3)(THF) was found to be superior to AlPh(3)(OEt(2)) or AlPhEt(2)(THF). Asymmetric aryl additions of AlAr(3)(THF) to aldehydes employing a loading of 5 mol % titanium(IV) complex 10 with a strategy of a slow addition of the aldehydes over 20 min were conducted. and the reactions produced optically active secondary alcohols in high yields with excellent enantioselectivities Of up to 94% ee. (C) 2009 Elsevier Ltd. All rights reserved

1,3-bis N-sulfonyl-(1R,2S)-1,3-diphenyl-2-aminopropanol benzene: An excellent ligand for titanium-catalyzed asymmetric AlPh3(THF) additions to aldehydes

Asymmetric AlPh3 (THF) additions to a wide variety of aldehydes catalyzed by a titanium catalyst of 20 mol % 1,3-bis[N-sulfonyl-(1R,2S)-1,3-diphenyl-2-aminopropanol] benzene (1) are reported. The catalytic system works excellently for aromatic aldehydes bearing either an electron-donating or an electron-withdrawing substituent on the aromatic ring to afford secondary diaryl alcohols in excellent isolated yields of >= 95% and excellent enantioselectivities of >= 94% ee. The phenyl addition to cinnamaldehyde or 2-furylaldehyde gave corresponding secondary alcohols in 85% and 95% ee, respectively. For aliphatic aldehydes, increasing enantioselectivities of the addition products in terms of increasing steric sizes of aldehydes are observed, and this trend goes from the linear I-pentanal (87% ee), the secondary cyclohexylaldehyde (95% ee) or the 2-methylpropanal (97% ee), to the tertiary 2,2-dimethylpropanal (99% ee)

Low-Cost Global Positioning System Tracking Collars for Use on Cattle

Commercially available global positioning system (GPS) tracking collars for cattle are cost prohibitive for most researchers. This paper presents a low-cost alternative to those collars (Knight GPS tracking collars) and compares their performance to a popular commercially available collar. A list of required materials and detailed instructions on fabrication are available in the supplementary content. Brangus cows (n = 8) were tracked with both LOTEK 3300 and Knight GPS tracking collars for 31 d beginning 14 March 2015 at the Chihuahuan Desert Rangeland Research Center 37 km north of Las Cruces, New Mexico. Locations were recorded every 10 min and used to calculate mean slope, elevation, distance from water, distance traveled per d, and elevation for each cow. No differences were detected (P ≥ 0.37) between collar types for location, slope, or distance from water. However, the distance traveled tended (P = 0.08) to be lower for Knight collars (6 171 m d− 1) compared with Lotek collars (7 104 m d− 1). Lotek collars recorded more (P ≤ 0.001) of the potential locations (99.9%) than the Knight collars (66.2%). Although the Knight collars failed to record all of the potential positions, they still provided a good indication of cattle locations on extensive pastures located in the Chihuahuan Desert.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information