ChemInform Abstract: REACTION OF UNSATURATED N‐CHLORAMINES. THE NITRENIUM ION QUESTION

Abstract

Die intramolekulare Cyclisierung von verschiedenen N‐Chloraminen wird bei unterschiedlichen Reaktionsbedingungen (Variation des Lösungsmittels, der Reaktionsdauer, des Katalysators) in neutralem Medium untersucht.

Stereo- and regiochemistries of the oxidations of 2-methoxy-5-tert-butyl-1,3,2-dioxaphosphorinanes and the cyclic methyl 3',5'-phosphite of thymidine by water/iodine and oxygen/AIBN to P-chiral phosphates. Oxygen-17 NMR assignment of phosphorus configuration to the diastereomeric thymidine cyclic methyl 3',5'-monophosphates

“…Trans ( 14), CD3CN, 80 °C, 160 Hz; CD3CN, 20 °C, 156 Hz. Line widths at 80 °C in CD3CN (P-decoupled) were relatively narrow for an l70 resonance: trans (14), 40 Hz; cis (13), 72 Hz. Small differences in ,70 NMR parameters for axial and equatorial 170 have been noted previously for cyclic 3',5'-monophosphate, diesters like 5.…”

“…Me2C(CN)0* + P(OR)3 -Me2CCN + OP(OR)3 ( 10) is quite reasonable. 14 We showed earlier15 that alkoxy radicals transfer oxygen to phosphorus (step 9) with retention of configuration, sequence 11. A phosphoranyl radical, 15, doubtless is Step 1 lb with Z = Me2C(CN)' is particularly favored. AIBN/02 oxidations of phenyl phosphites occur readily, whereas with Z-BuOOBu-Z displacement of phenoxy radical by ZerZ-butoxy radical results.…”

“…While our work was in progress, a preliminary account of the retentive stereochemistry of the H20/I2 oxidation of S'-O-thyminyl 3'-0-thymidine methyl phosphite was reported17 as well as a preliminary study of the stereochemistry of H20/I2 oxidation of phosphites 1 and 3, which our work confirms.17 However, in the earlier work no data regarding the degree of stereospecificity with 1 and 3 were given, as only a single diastereomer (cis) of 1 and 3 was used. A number of H2180/I2 oxidations of dinucleoside alkyl phosphites have been shown to be regiospecific and stereospecific,2b although the retentive nature (14) Walling, C.; Rablnowitz, R. J. Am.…”

Cage azapolycyclics. An investigation of the cyclization orientation to twisted- or nontwisted-tricyclic azabridged molecules. Synthesis and structure determination by 250-MHz nuclear magnetic resonance spectroscopy

“…The same compound is formed (56%) besides five other products (18%) and starting amine (26%) when 1 is treated in boiling methanol for 36 h. The mechanisms of these reactions will be discussed elsewhere. 13 The comparison of the NMR spectrum of 2 with those of 6 and 7 (see below) allows us to assign without any doubt a "nontwisted" homobrendane structure 214 to the solvolysis product of JV-chloroamine 1.…”

“…Furthermore, on the basis of chemical arguments, the methoxy group was expected to be exo. 13 Consequently proton H8 should appear as a doublet (90°dihedral angle between C5H5 and CeHg) which must be the one at 2.56 ppm. The signal at 3.27 ppm can only be due to proton H5 deshielded by the methoxy group.…”