Abstract
G3(MP2)-RAD calculations provide activation energies for intramolecular homolytic substitution in the 4-(alkylselenoxo)butyl and 4-(alkylselendioxo)butyl radicals ranging from 21–39 kJ mol−1, and 143–170 kJ mol−1for the selenoxide and selenone, respectively. Arrhenius data translate into rate constants for ring-closure of 1.5×105−2.5×108s−1(80°) for the selenoxides, and 5.4×10−14−5.1×10−11s−1(80°) for the corresponding selenones. NBO analyses show alkyl radicals are electrophilic during homolytic substitution at selenoxide selenium. The dominant orbital interaction in the transition state is worth 2413 kJ mol−1and involves the SOMO and the lone-pair of electrons on selenium. The corresponding selenones are calculated to ring-close through transition states in which alkyl radicals are nucleophilic, but involve weak (SOMO-> σ* and SOMO-> π*) interactions. Consequently, this chemistry is not viable for selenones because of the lack of lone-pairs of electrons on the chalcogen.
| Original language | English |
|---|---|
| Pages (from-to) | 7790-7795 |
| Number of pages | 6 |
| Journal | Tetrahedron |
| Volume | 72 |
| Issue number | 48 |
| DOIs | |
| Publication status | Published - 1 Jan 2016 |
| Externally published | Yes |
Keywords
- Computational chemistry
- Homolytic substitution
- Radical
- Selenium
- Selenone
- Selenoxide
Cite this
}
Intramolecular homolytic substitution in selenoxides and selenones. / Hancock, Amber N.; Kyne, Sara H.; Aitken, Heather M.; Schiesser, Carl H.
In: Tetrahedron, Vol. 72, No. 48, 01.01.2016, p. 7790-7795.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Intramolecular homolytic substitution in selenoxides and selenones
AU - Hancock, Amber N.
AU - Kyne, Sara H.
AU - Aitken, Heather M.
AU - Schiesser, Carl H.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - G3(MP2)-RAD calculations provide activation energies for intramolecular homolytic substitution in the 4-(alkylselenoxo)butyl and 4-(alkylselendioxo)butyl radicals ranging from 21–39 kJ mol−1, and 143–170 kJ mol−1for the selenoxide and selenone, respectively. Arrhenius data translate into rate constants for ring-closure of 1.5×105−2.5×108s−1(80°) for the selenoxides, and 5.4×10−14−5.1×10−11s−1(80°) for the corresponding selenones. NBO analyses show alkyl radicals are electrophilic during homolytic substitution at selenoxide selenium. The dominant orbital interaction in the transition state is worth 2413 kJ mol−1and involves the SOMO and the lone-pair of electrons on selenium. The corresponding selenones are calculated to ring-close through transition states in which alkyl radicals are nucleophilic, but involve weak (SOMO-> σ* and SOMO-> π*) interactions. Consequently, this chemistry is not viable for selenones because of the lack of lone-pairs of electrons on the chalcogen.
AB - G3(MP2)-RAD calculations provide activation energies for intramolecular homolytic substitution in the 4-(alkylselenoxo)butyl and 4-(alkylselendioxo)butyl radicals ranging from 21–39 kJ mol−1, and 143–170 kJ mol−1for the selenoxide and selenone, respectively. Arrhenius data translate into rate constants for ring-closure of 1.5×105−2.5×108s−1(80°) for the selenoxides, and 5.4×10−14−5.1×10−11s−1(80°) for the corresponding selenones. NBO analyses show alkyl radicals are electrophilic during homolytic substitution at selenoxide selenium. The dominant orbital interaction in the transition state is worth 2413 kJ mol−1and involves the SOMO and the lone-pair of electrons on selenium. The corresponding selenones are calculated to ring-close through transition states in which alkyl radicals are nucleophilic, but involve weak (SOMO-> σ* and SOMO-> π*) interactions. Consequently, this chemistry is not viable for selenones because of the lack of lone-pairs of electrons on the chalcogen.
KW - Computational chemistry
KW - Homolytic substitution
KW - Radical
KW - Selenium
KW - Selenone
KW - Selenoxide
UR - http://www.scopus.com/inward/record.url?scp=84992188113&partnerID=8YFLogxK
U2 - 10.1016/j.tet.2016.08.083
DO - 10.1016/j.tet.2016.08.083
M3 - Article
VL - 72
SP - 7790
EP - 7795
JO - Tetrahedron
JF - Tetrahedron
SN - 0040-4020
IS - 48
ER -