Face Selection in Reactions of 5,7-Diazaadamantan-2-one Derivatives: Mutual Influence of Remote Substituents
摘要:
When one of the nitrogen atoms in 5,7-diazaadamantan-2-one(1) (4) is quaternized, for example, as in 3-O, carbonyl reduction occurs principally at the zu face to give alcohol (E)-6-O, in accord with Cieplak-type transition state hyperconjugation. The ratio in this reduction is somewhat less than in that of the previously reported monoaza N-oxide 2-O, which is attributed to the effect of hyperconjugation in the initial state of 3-O. If the parent diaza ketone 4 is reduced first to the corresponding diaza alcohol 5 and if this is then oxidized to 6-O, the Z-isomer is the principal product. The stereochemistry of this latter reaction is also considered to be a result of extended hyperconjugation. Virtually identical data are obtained with the methyl iodide salts. It is concluded that the effect of remote substituents is mutual and that this fact can be exploited to influence, even reverse, the stereochemical outcome of a synthesis by manipulation of the sequence of the individual steps.
Face Selection in Reactions of 5,7-Diazaadamantan-2-one Derivatives: Mutual Influence of Remote Substituents
摘要:
When one of the nitrogen atoms in 5,7-diazaadamantan-2-one(1) (4) is quaternized, for example, as in 3-O, carbonyl reduction occurs principally at the zu face to give alcohol (E)-6-O, in accord with Cieplak-type transition state hyperconjugation. The ratio in this reduction is somewhat less than in that of the previously reported monoaza N-oxide 2-O, which is attributed to the effect of hyperconjugation in the initial state of 3-O. If the parent diaza ketone 4 is reduced first to the corresponding diaza alcohol 5 and if this is then oxidized to 6-O, the Z-isomer is the principal product. The stereochemistry of this latter reaction is also considered to be a result of extended hyperconjugation. Virtually identical data are obtained with the methyl iodide salts. It is concluded that the effect of remote substituents is mutual and that this fact can be exploited to influence, even reverse, the stereochemical outcome of a synthesis by manipulation of the sequence of the individual steps.
Stetter et al., Chemische Berichte, 1959, vol. 92, p. 2057,2060
作者:Stetter et al.
DOI:——
日期:——
ASLANOV X. A.; INOYATOVA D. A.; KOSOVSKIJ A. V.; ATABAEV R., SB. NAUCH. TR. TASHKENT. YH-T, 1979, HO 595, 83-86
作者:ASLANOV X. A.、 INOYATOVA D. A.、 KOSOVSKIJ A. V.、 ATABAEV R.
DOI:——
日期:——
HYDROPHILIC CROSSLINKED POLYMER
申请人:Joehnck Matthias
公开号:US20110091727A1
公开(公告)日:2011-04-21
The present invention relates to a hydrophilic crosslinked polymer, preferably in the form of porous particles, and to the preparation and use thereof. The polymer according to the invention is produced by polymerisation from chain-forming hydrophilic vinyl ethers and crosslinking, preferably heterocyclic divinyl ethers.