01834nas a2200253   4500008004100000022001400041245015100055210006900206260007700275300001400352520086900366653002001235653002501255653001301280653002401293100001901317700001801336700001801354700001601372700001701388700002401405700002301429856012801452       2014                        eng d  a1434-193X00aSynthesis of alpha,beta-unsaturated delta-lactones by vinyl acetate mediated asymmetric cross-aldol reaction of acetaldehyde: mechanistic insights0 aSynthesis of alphabetaunsaturated deltalactones by vinyl acetate  aBOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcAUG  a5247-52553 a<p>A tandem asymmetric cross-aldol reaction involving the in situ generation of acetaldehyde from vinyl acetate has been developed that may resolve the challenges associated with the handling of acetaldehyde. The simple protocol, mild reaction conditions and unique harmony of an organocatalyst with a biocatalyst make this method a valuable tool for the synthesis of asymmetric beta-hydroxy aldehydes. By using this methodology we have accessed alpha,beta-unstaurated delta-lactones as well as isochromenones with high enantioselectivities from both asymmetric beta-hydroxy aldehydes and ketones. Systemic density functional theory (DFT) studies were also performed to gain mechanistic insights into the role of hydrogen bonding in the asymmetric cross-aldol reaction of acetaldehyde and in the key cis/trans isomerisation step in the synthesis of d-lactones.</p>10aAldol reactions10aasymmetric catalysis10alactones10areaction mechanisms1 aKumar, Manjeet1 aKumar, Arvind1 aRizvi, Masood1 aMane, Manoj1 aVanka, Kumar1 aTaneja, Subhash, C.1 aShah, Bhahwal, Ali  uhttps://library.ncl.res.in/content/synthesis-alphabeta-unsaturated-delta-lactones-vinyl-acetate-mediated-asymmetric-cross-002144nas a2200205   4500008004100000245012100041210006900162260000800231300002500239490000600264520140300270100001901673700001801692700002201710700001801732700001801750700002101768700001801789856013101807       2018                        eng d00aNew insights towards strikingly improved room temperature ethanol sensing properties of p-type Ce-doped SnO2 sensors0 aNew insights towards strikingly improved room temperature ethano  cMAY  aArticle Number: 80790 v83 aIn this article, room temperature ethanol sensing behavior of p-type Ce doped SnO2 nanostructures are investigated successfully. Interestingly, it is examined that the abnormal n to p-type transition behavior is caused by Ce doping in SnO2 lattice. In p-type Ce doped SnO2, Ce ion substituting the Sn is in favor of generating excess holes as oxygen vacancies, which is associated with the improved sensing performance. Although, p-type SnO2 is one of the important materials for practical applications, it is less studied as compared to n-type SnO2. Pure and Ce doped SnO2 nanostructures were successfully synthesized by chemical co-precipitation method. The structure, surface morphology, unpaired electrons (such as free radicals), and chemical composition of obtained nanoparticleswere studied by various kinds of characterization techniques. The 9% Ce doped SnO2 sensors exhibit maximum sensor response of similar to 382 for 400 ppm of ethanol exposure with fast response time of similar to 5 to 25 sec respectively. Moreover, it is quite interesting that such enhancement of ethanol sensing is unveiled at room temperature, which plays a key role in the quest for better ethanol sensors. These remarkably improved sensing results are attributed to uniformly distributed nanoparticles, lattice strain, complex defect chemistry and presence of large number of unpaired electrons on the surface.1 aKumar, Manjeet1 aBhatt, Vishwa1 aAbhyankar, A., C.1 aKim, Joondong1 aKumar, Akshay1 aPatil, Sagar, H.1 aYun, Ju-Hyung  uhttps://library.ncl.res.in/content/new-insights-towards-strikingly-improved-room-temperature-ethanol-sensing-properties-p-type