Syntheses, Characterization, and Molecular Mechanics Calculations of Optically Active Silatrane Derivatives

Abstract

A series of optically active silatrane derivatives, [Si{N(CHRCH(2)O)(CH(2)CH(2)O)(2)}X] (R = Me, i-Pr; X = Ph, OMe) has been synthesized by the reaction of optically active triethanolamine derivatives with XSi(OMe)(3), and characterized by (1)H NMR, (13)C NMR, (29)Si NMR, and mass spectroscopy, and the structures of six compounds have been determined by X-ray analysis. Molecular mechanics methods have also been employed to obtain the energy-minimized structures. The (29)Si NMR chemical shifts and the lengths of Si-N determined by X-ray analysis are sensitive to the bulkiness of the substituent (R). The Si-X bond lengths (X: trans position to nitrogen) do not appreciably differ from one another. The MM2 calculations indicated that the substituent exists in the equatorial position, and the results are in agreement with those of X-ray analysis and (1)H NMR spectroscopy. Crystallographic data: [R = H; X = OMe], C(7)H(15)NO(4)Si, orthorhombic, Pna2(1), a = 13.407(1) Å, b = 8.761(2) Å, c = 8.191(1) Å, Z = 4; [R = Me; X = OMe], C(8)H(17)NO(4)Si, orthorhombic, P2(1)2(1)2(1), a = 10.110(3) Å, b = 11.083(2) Å, c = 9.474(2) Å, Z = 4; [R = i-Pr; X = OMe], C(10)H(21)NO(4)Si, monoclinic, P2(1), a = 8.481(1) Å, b = 7.805(1) Å, c = 10.218(2) Å, beta = 111.31(1) degrees, Z = 2; [R = Me; X = Ph], C(13)H(19)NO(3)Si, orthorhombic, P2(1)2(1)2(1), a = 8.813(1) Å, b = 11.137(2) Å, c = 13.757(1) Å, Z = 4; [R = i-Pr; X = Ph], C(15)H(23)NO(3)Si, orthorhombic, P2(1)2(1)2(1), a = 8.365(1) Å, b = 13.538(2) Å, c = 13.841(2) Å, Z = 4.

Theoretical study of the geometrical, energetic and NMR properties of atranes

“…The results obtained from each atom are in concordance with the usual ones for similar chemical connectivities. A relationship between the chemical shift of the atoms X(Y) and the associated X/Y interaction has not been found, although some authors [ [13]] have found linear relationships between the 29 Si NMR chemical shifts (ppm) and the Si/N distances (Å) in the case of derivatives of general formula 99, but they correspond to the perturbation of a [3.3.3]trioxasilatrane by substituents R and X.…”

“…Note that we called saturated atranes those where their X and Y atoms are connected by carbon atoms exclusively. We will not discuss the D and L stereochemistry of atranes [12,13].…”

Silatranes and Their Tricyclic Analogs

“…Use of H 2 PtCl 6 as a catalyst favors transetherification of the two triethoxysilanes as shown by the increased silatrane yields 50 . Organyltriethoxysilanes react with racemic 59 or optically active triethanolamine derivatives 60,61 to afford 4-substituted 1-organylsilatranes (equation 8).…”

“…Silatranes and their tricyclic analogs 1453 substituted silatranes are formed in a similar way 62 . Reaction 2 can also be applied to the synthesis of a number of 1-alkoxy-1,53,61 and 1-aryloxysilatranes 33,63 as illustrated by equations 9 61 …”

“…1 H NMR studies of 3-methylsilatranes 238 , 4-organylsilatranes 61 and diastereomeric 3,7-dimethyl-and 3,7,10-trimethylsilatranes 238,239 revealed conformational rigidity of their substituted five-membered rings and the equatorial position of the C-substituent. It was shown that for most 3,7-dimethyl-and 3,7,10-trimethylsilatranes the diastereomer distributions are nearly statistical, indicating a kinetic control of the reactions leading to the formation of the silatrane cage 238 .…”