Coupling constants amines

The H and 13CNMR spectra of various cyclopentazepines have been recorded (Tables 1 and 2), as has the HNMR spectrum of 7V,7V-dimethylcyclopent[e]azepin-l-amine.68 A detailed analysis of geminal and long-range 13C-H coupling constants for cyclopent[c]azepine is also available.87 The HNMR spectra of 9//-pyrrolo[l,2-a]azepin-9-one (8b) and its fully delocalized cation have been recorded in various solvents.7... 

Table 3.24 NMR coupling constants for platinum amine complexes [156]...

The observed ya-SCS(X) values in 7-exo-substituted norcaranes 97 (225) and those of M(CH3)3 (M = Si, Ge, Sn, or Pb) in cyclohexyl and bicy-clo[2.2. l]heptane derivatives (133) were later interpreted on the same basis. The back-lobe-overlap treatment was further supported by interpretations of H and 13C contact shifts of aliphatic amine signals in the presence of nickel acetyl-acetonate and by INDO calculations (226,227). Additional support came from extensive investigations of the structure dependence of three-bond coupling constants 3JCX (X = H, C, or F) (228,229), although the interpretation of these data has been subjected to criticism (230). 

A study on the conjugate acids of dihydro-6//-dibenz[c,e]azepines has demonstrated the validity of the Karplus equation for determining H—N—C—H coupling constants in secondary and tertiary amines of known rigid conformation (73CJC2433). 

A qualitatively similar dependence of ADh on boron orbital hybridization is noted in boron hydrides (104). -1bh = 81 cps for BHr where boron is tetrahedral while ABH = 136 cps for borazole where boron presumably is sp2. A ijh for BH3 adducts with ethers, amines, and phosphines range between 90 and 103 cps and for these compounds boron quadrupole coupling constants have been interpreted (22) in terms of a boron hybridization intermediate between sp2 and sp2. However, the simple dependence of... 

We added the acetylene to aldehyde 12 now because this step is not compatible with a protected guanidine. Treatment of 43 with EtMgBr to form the acetylide and addition of aldehyde 12 afforded 54% of 45 and 32% of 44. Under the basic conditions, the secondary amine adds to the carbamate to form the oxazolidinone ring. The decrease in the geminal coupling constant of the methylene hydrogens adjacent to the nitrogen from 11 Hz in 43 to 8 Hz in oxazolidinone 45 is characteristic of the... 

Fig. 9. Temperature dependence of the (metal) hyperfine coupling constant, expressed as percent atomic character, as a function of temperature for solutions of (a) potassium (MK), (b) rubidium ( "Rb), and (c) cesium (,J Cs) in amines, ethers, and HMPA. The experimental data are from a variety of sources, and outlined elsewhere (.16). Open symbols denote parameters from fluid solution studies shaded symbols are from frozen solutions in HMPA. Solvent identification as in Figure 8, and BuA = butylamine, i-PA and n-PA are isopropylamine and n-propylamine. 

Two conceptually different models have been proposed to explain the temperature dependence of the (metal) hyperfine coupling constant and electronic ge factor in metal-amine and metal-ether solutions. 

The NMR spectrum of a thienamycin derivative with protecting groups on the amine and carboxylic acids is shown below. Try your hand at interpreting it before you read the explanation below. Your aim is to find the coupling constant across the four-membered ring,... 

A more serious situation arises when we treat this product with base. An unusual elimination product is formed, in which the amine group has moved next to the ketone. The reaction is interesting for this point alone, and one of the problems at the end of the chapter asks you to suggest a mechanism. But there is added interest, because the product is also formed as a single geometrical isomer, E or Z. But which one There is a hydrogen atom at one end of the alkene but not at the other so we can t use 3/ coupling constants to find out as there aren t any. 

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