Spectroscopy compounds

Upon nmr spectroscopy, Compounds C and D were revealed to be stereoisomers. 

The peaks were collected and freed from adjacent peaks and shoulders by further HPLC, before examination by mass spectrometry and electronic absorption spectroscopy. Compounds of the following molecular masses were progressively eluted on reverse-phase HPLC 114, 345, 178, 194, 194, 194, 192, 272, 272,... 

The mono- (283) and bis-phosphate (284) derivatives of D-threo-2,5-hexodiulose ( 5-keto-D-fructose, 260) were synthesized enzymically and purified by anion-exchange chromatography. The proportions, ring size, and anomeric configuration were determined by 31P and 13C NMR spectroscopy. Compound 283 was found to exist preponderantly (80%) in the /f-pyranose form, with the remainder being present in the 2R.5R-furanose form. Compound 284 assumes two different furanose forms in solution, one ( 80%) being the 2i ,5i -furanose and the other the 2i ,5S -furanose.500... 

Nupharolidine (9) was isolated from Nuphar lutea (28). Its structure was determined by IR, 1H-NMR, and mass spectroscopy. Compound 9 was the first example of a Nuphar alkaloid with a hydroxyl group in the quinolizidine system. This alkaloid is isomeric with castoramine (59), nuphamine, and isocastora-mine (10). 

Summary Treatment of Si(NCO)4 or Si(NCS)4 with 4-aminopent-3-en-2-ones yielded novel neutral hexacoordinate silicon(IV) complexes with an S/O2N4 framework, compounds 3-6. These silicon(IV) complexes were characterized in the solid state by single-crystal X-ray diffraction and Si VACP/MAS NMR spectroscopy. Compounds 3-5 crystallized as the (OC-6-12)-isomer, and 6 was isolated as the rranj-isomer. 

The H-bond complexes formed between phenol derivatives and bis-l,8-(dimethylamino)-naphthalene (175) in 1,2-dichloroethane and tetrachloroethylene solution were characterized by FTIR spectroscopy. Compound 175 acts as an effective proton sponge for its ability to form a six-membered chelate-type structure including aN H N moiety. The stability constants of the 1 1 and 2 1 complexes are strongly dependent on the pXa value of the phenols and increase also with the polarity of the solvent. No complex formation was detected in tetrachloroethylene when H was replaced by... 

As a result of this work, it was discovered that substance (11) undergoes another type of acid catalyzed ring closure on treatment with BF3 etherate at room temperature (22, 23). This affords a crystalline compound named isodehydropanaxadiol (29) in 28% yield, whose structure was deduced by mass and NMR spectroscopy. Compound (29) was also isolated from the crude hydrolysate of the saponin mixture with dilute mineral acid as one of the minor products. 

The salts [CTHejNaOJpgXa]. HjO (X = C1 1, Br 2 or I 3) have been synthesised and characterised by various techniques, including Cl (1), Br (2) and I (3) NQR spectroscopy. Compounds 1 and 2 were iso-structural, but 3 differed. Both 1 and 2 contained trigonal planar HgX3" ions, H-bonded with H2O and cations into 2D sheets parallel to the ac plane. These sheets were connected by double chains of Hg—X interionic bonds along the b direction, resulting in a tbp about Hg with two long... 

The selenium analogue of (13) has been generated by the photolysis of 2,1,3-benzoselenadiazole 1-oxide and identified as a transient species, having the structure (14), by u.v. spectroscopy. Compound (14) gives the selenium analogue of (7 R = N=S=S) as another transient species upon treatment with Seg, generated by flash photolysis (see also Chap. 6, p. 295). 

As is obvious from Scheme 1, to obtain dinitroalkanes 6A and 6B, a sequence of reactions was followed. The intermediate compounds obtained in this process were known compounds. These were characterized by means of physical constants and infrared (IR) and proton magentic resonance (PMR) spectroscopy. Compounds 6A, 6B, 7A, 8A and 8B were found to be new compounds. 

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