TY - JOUR
T1 - Homo- and heteroanionic alkali metal aza-enolate aggregates derived from o-methylvalerolactim ether
AU - Andrews, Philip
AU - Bull, Steven
AU - Koutsaplis, Magdaline
PY - 2010
Y1 - 2010
N2 - The reaction of o-valerolactim ether with BuM (M = Li, Na, K) in the presence of the Lewis donors thf, tmeda, pyridine and pmdta resulted in the crystallisation and structural characterisation of a series of homo- and heteroanionic aggregates, which are also either homo or heterobimetallic. All the structures incorporate an aza-enolate (1-aza-allyl) anion (= R) derived from deprotonation of the lactim ether at the alpha-C, and its subsequent electronic rearrangement such that the metal bonds to the amido N. Lithiation resulted in crystals of [R-3 R(Me2SiO) Li-4 center dot(thf)(4)], 1, with Me2SiO- incorporated from the base induced decomposition of silicone grease; the linked dimer [R4Li4 center dot(tmeda)(3)], 2, which has both terminal and bridging tmeda molecules; the octanuclear cluster [R-6-mu(6)-O-Li-8 center dot(pyr)(2)], 3, which is constructed around an O2- anion; and [R(CH2=CHO)(2)Li-3 center dot pmdta](2), 4, which incorporates lithium ethenolate, the base induced decomposition product of thf. Sodiation resulted in crystals of the simple dimeric complex [RNa center dot tmeda](2), 5, while potassiation resulted in the heterobimetallic cluster [R(MeO)KLi center dot(tmeda)](4), 6, incorporating a MeO anion due to its nucleophilic displacement from the valerolactim ether as MeOK by Bu-n and subsequent anion exchange with (BuOLi)-Bu-t. Solution NMR studies on the reaction between RH and (BuLi)-Bu-t in the absence of a Lewis donor revealed that both the rate of deprotonation at the alpha-carbon and nucleophilic substitution of the ether functionality decrease substantially. The cyclic 2-Bu-t-imine, as the thermodynamic product, becomes the dominant product, indicating that a Lewis donor solvent is necessary for efficient deprotonation to occur.
AB - The reaction of o-valerolactim ether with BuM (M = Li, Na, K) in the presence of the Lewis donors thf, tmeda, pyridine and pmdta resulted in the crystallisation and structural characterisation of a series of homo- and heteroanionic aggregates, which are also either homo or heterobimetallic. All the structures incorporate an aza-enolate (1-aza-allyl) anion (= R) derived from deprotonation of the lactim ether at the alpha-C, and its subsequent electronic rearrangement such that the metal bonds to the amido N. Lithiation resulted in crystals of [R-3 R(Me2SiO) Li-4 center dot(thf)(4)], 1, with Me2SiO- incorporated from the base induced decomposition of silicone grease; the linked dimer [R4Li4 center dot(tmeda)(3)], 2, which has both terminal and bridging tmeda molecules; the octanuclear cluster [R-6-mu(6)-O-Li-8 center dot(pyr)(2)], 3, which is constructed around an O2- anion; and [R(CH2=CHO)(2)Li-3 center dot pmdta](2), 4, which incorporates lithium ethenolate, the base induced decomposition product of thf. Sodiation resulted in crystals of the simple dimeric complex [RNa center dot tmeda](2), 5, while potassiation resulted in the heterobimetallic cluster [R(MeO)KLi center dot(tmeda)](4), 6, incorporating a MeO anion due to its nucleophilic displacement from the valerolactim ether as MeOK by Bu-n and subsequent anion exchange with (BuOLi)-Bu-t. Solution NMR studies on the reaction between RH and (BuLi)-Bu-t in the absence of a Lewis donor revealed that both the rate of deprotonation at the alpha-carbon and nucleophilic substitution of the ether functionality decrease substantially. The cyclic 2-Bu-t-imine, as the thermodynamic product, becomes the dominant product, indicating that a Lewis donor solvent is necessary for efficient deprotonation to occur.
UR - http://pubs.rsc.org.ezproxy.lib.monash.edu.au/en/content/articlepdf/2010/nj/c0nj00088d
U2 - 10.1039/c0nj00088d
DO - 10.1039/c0nj00088d
M3 - Article
SN - 1144-0546
VL - 34
SP - 1678
EP - 1691
JO - New Journal of Chemistry
JF - New Journal of Chemistry
IS - 8
ER -