Solution structures of lithium enolates, phenolates, carboxylates, and alkoxides in the presence of N,N,N',N'-tetramethylethylenediamine: a prevalence of cyclic dimers.
The method of continuous variation was used to characterize lithium enolates, phenolates, carboxylates, and alkoxides solvated by N,N,N',N'-tetramethylethylenediamine (TMEDA). The method relies on characterizing an ensemble of homo- and heteroaggregates using (6)Li NMR spectroscopy. A combination of aggregate counts and symmetries, nearly statistical distributions, and quantitative parametric fits revealed that cyclic dimers are the dominant forms. Nonstatistical distributions favoring heteroaggregated dimers were observed when hindered enolates and carboxylates were mixed with unhindered enolates. Hindered (tertiary) alkoxides form higher aggregates (possibly hexamers), whereas hindered lithium phenolates appear to form TMEDA-solvated monomers.
Gruver
Jocelyn M
JM
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
Liou
Lara R
LR
McNeil
Anne J
AJ
Ramirez
Antonio
A
Collum
David B
DB
D002264:Carboxylic Acids / Q000737:chemistry*; D019281:Dimerization; D005029:Ethylenediamines / Q000737:chemistry*; D062385:Hydroxybenzoates / Q000737:chemistry*; D008094:Lithium; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012996:Solutions / Q000737:chemistry
D002264:Carboxylic Acids; D005029:Ethylenediamines; D062385:Hydroxybenzoates; D012996:Solutions; D008094:Lithium; C017616:phenolic acid
Methods Enzymol. 1982;87:509-25
7176926
Chem Rev. 2006 Jul;106(7):2596-616
16836294
Org Lett. 2002 Feb 21;4(4):573-5
11843594
J Am Chem Soc. 2004 May 19;126(19):5938-9
15137738
J Org Chem. 2001 Dec 28;66(26):9005-10
11749634
Angew Chem Int Ed Engl. 2006 Nov 20;45(45):7506-25
17103481
Angew Chem Int Ed Engl. 1999 Nov 15;38(22):3367-3370
10602197
J Am Chem Soc. 2005 Apr 6;127(13):4965-75
15796563
J Am Chem Soc. 2005 Apr 20;127(15):5655-61
15826205
J Am Chem Soc. 2008 Apr 9;130(14):4859-68
18336025
J Am Chem Soc. 2001 Aug 22;123(33):7973-7
11506552
J Am Chem Soc. 2004 Jan 21;126(2):484-5
14719943
Angew Chem Int Ed Engl. 2007;46(17):3002-17
17387670
Chem Rev. 2006 Jul;106(7):2734-93
16836298
J Am Chem Soc. 2004 Dec 22;126(50):16559-68
15600361
J Am Chem Soc. 2006 Aug 9;128(31):10326-36
16881665
J Org Chem. 2006 May 26;71(11):4031-9
16709041
Angew Chem Int Ed Engl. 2005 Feb 25;44(10):1448-54
15724254
Org Lett. 2001 Aug 9;3(16):2599-601
11483070