Aldehydes spectroscopic analysis

The reaction of the aldehyde 256 with proline gave a product which was not the expected dihydiodibenz[r,f ]azepinc 257. Spectroscopic analysis revealed that this new product was an oxazolidine 259 (obtained as a single isomer) resulting from the 1,3-cycloaddition of the azomethine ylide 258 to the precursor aldehyde 256 (Scheme 38) <1999J(P1)2605>. 

The second part of the chapter deals with several kinds of asymmetric reactions catalyzed by unique heterobimetallic complexes. These reagents are lanthanoid-alkali metal hybrids which form BINOL derivative complexes (LnMB, where Ln = lanthanoid, M = alkali metal, and B = BINOL derivative). These complexes efficiently promote asymmetric aldol-type reactions as well as asymmetric hydrophosphonylations of aldehydes (catalyzed by LnLB, where L = lithium), asymmetric Michael reactions (catalyzed by LnSB, where S = sodium), and asymmetric hydrophosphonylations of imines (catalyzed by LnPB, where P = potassium) to give the corresponding desired products in up to 98% ee. Spectroscopic analysis and computer simulations of these asymmetric reactions have revealed the synergistic cooperation of the two different metals in the complexes. These complexes are believed to function as both Brpnsted bases and as Lewis acids may prove to be applicable to a variety of new asymmetric catalytic reactions.1,2... 

The formation of polymer bound products was confirmed by infrared spectroscopic analysis. These catalysts were employed for an enantioselctive addition of diethylzinc to aldehyde (Scheme 2). In order to obtain a good reaction medium the reaction was initially studied with varying amounts of catalyst 3A in hexane, THE and toluene as solvents. Moderate results (ee 20-32% yield 70-81%) were obtained in hexane and THE. However, the best results were obtained with toluene. Therefore, toluene became the solvent of choice for the rest of the investigation. 

Kalvin and Woodard (116) synthesized samples of homoserine labeled in all of the diastereotopic hydrogens. In their first synthesis, they used R)- and (S)-alpine boranes to reduee the deuterated aldehyde 109. (/ )-Alpine borane gave the (S)-[ HJ alcohol 110, Hg = H, (S)-alpine borane gave the corresponding (/ )-alcohol 110, NMR spectroscopic analysis of... 

Some of the cuticular lipids are also suitable for spectroscopic analysis. )3-Diketones absorb at 273 nm so that ultraviolet spectroscopy can be used (Tulloch, 1976). The functional groups of various fractions obtained by TLC can be confirmed by infrared analysis. Aldehydes and )8-diketones give useful shifts when examined by nuclear magnetic resonance and this technique can be made considerably more sensitive by the application of C-NMR for some wax components (Tulloch, 1976). 

The reactions of NaOH with cellulose in natural fiber yielded cellulose-ONa compound and removed impurities from the fiber surface [11,12]. This is confirmed by the FTIR spectroscopic analysis as shown in Figure 14.1. The FTIR spectrum of the raw wood clearly shows the absorption band in the region of3407 cm, 2917 cm and 1736 cm due to O-H, C-H and C = O stretching vibration respectively. These absorption bands are due to hydroxyl groups in cellulose, carbonyl groups of acetyl ester in hemi-cellulose and carbonyl aldehyde in lignin. 

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