Schlosser's base (or Lochmann-Schlosser base) describes various superbasic mixtures of an alkyllithium compound and a potassium alkoxide.[1][2] The reagent is named after Manfred Schlosser, although he uses the term LICKOR superbase (LIC denoting the alkyllithium, and KOR denoting the potassium alkoxide). The superbasic nature of the reagent is a consequence of the in situ formation of the corresponding organopotassium compound, as well as changes to the aggregation state of the alkyllithium species.
The high reactivity of Schlosser's base is exploited in synthetic organic chemistry for the preparation of organometallic reagents. For example, potassium benzyl can be prepared from toluene using this reagent. Benzene and cis/trans-2-butene are also readily metalated by Schlosser's base. Toluene, benzene, and butenes react only slowly with alkyllithium reagents and not at all with potassium alkoxides, yet they react rapidly with a mixture of the two. Although there are similarities, the reactivities of Schlosser's base and the isolated alkylpotassium reagent are not identical.[3]
Structure
The structure of Schlosser's base is complex. A study of the base prepared from neopentyllithium (neo-C5H11Li) and potassium t-butoxide (t-BuOK) has led to the spectroscopic and crystallographic identification of a series of constituent bimetallic clusters:
LixKy(neo-C5H11)z(t-BuO)w, x + y = z + w = 7 or 8,
in equilibrium with neopentylpotassium (neo-C5H11K) and lithium t-butoxide (t-BuOLi).[4]
References
^Schlosser, Manfred (1988). "Superbases for organic synthesis". Pure and Applied Chemistry. 60 (11): 1627–1634. doi:10.1351/pac198860111627.
^Schlosser, Manfred (2005-01-07). "The 2×3 Toolbox of Organometallic Methods for Regiochemically Exhaustive Functionalization". Angewandte Chemie International Edition. 44 (3): 376–393. doi:10.1002/anie.200300645. PMID 15558637.
^Schlosser, Manfred; Strunk, Sven (1984). "The "super-basic" butyllithium/potassium tert-butoxide mixture and other lickor-reagents". Tetrahedron Letters. 25 (7): 741–744. doi:10.1016/s0040-4039(01)80014-9.
^Benrath, Philipp; Kaiser, Maximilian; Limbach, Thomas; Mondeshki, Mihail; Klett, Jan (2016-08-26). "Combining Neopentyllithium with Potassium tert-Butoxide: Formation of an Alkane-Soluble Lochmann–Schlosser Superbase". Angewandte Chemie International Edition. 55 (36): 10886–10889. doi:10.1002/anie.201602792. ISSN 1521-3773. PMID 27392232.
March 03, 2023
schlosser, base, lochmann, schlosser, base, describes, various, superbasic, mixtures, alkyllithium, compound, potassium, alkoxide, reagent, named, after, manfred, schlosser, although, uses, term, lickor, superbase, denoting, alkyllithium, denoting, potassium, . Schlosser s base or Lochmann Schlosser base describes various superbasic mixtures of an alkyllithium compound and a potassium alkoxide 1 2 The reagent is named after Manfred Schlosser although he uses the term LICKOR superbase LIC denoting the alkyllithium and KOR denoting the potassium alkoxide The superbasic nature of the reagent is a consequence of the in situ formation of the corresponding organopotassium compound as well as changes to the aggregation state of the alkyllithium species Preparation and reactivity EditCommonly the mixture called Schlosser s base is produced by combining n butyllithium and potassium tert butoxide in a one to one ratio The high reactivity of Schlosser s base is exploited in synthetic organic chemistry for the preparation of organometallic reagents For example potassium benzyl can be prepared from toluene using this reagent Benzene and cis trans 2 butene are also readily metalated by Schlosser s base Toluene benzene and butenes react only slowly with alkyllithium reagents and not at all with potassium alkoxides yet they react rapidly with a mixture of the two Although there are similarities the reactivities of Schlosser s base and the isolated alkylpotassium reagent are not identical 3 Structure EditThe structure of Schlosser s base is complex A study of the base prepared from neopentyllithium neo C5H11Li and potassium t butoxide t BuOK has led to the spectroscopic and crystallographic identification of a series of constituent bimetallic clusters LixKy neo C5H11 z t BuO w x y z w 7 or 8 in equilibrium with neopentylpotassium neo C5H11K and lithium t butoxide t BuOLi 4 References Edit Schlosser Manfred 1988 Superbases for organic synthesis Pure and Applied Chemistry 60 11 1627 1634 doi 10 1351 pac198860111627 Schlosser Manfred 2005 01 07 The 2 3 Toolbox of Organometallic Methods for Regiochemically Exhaustive Functionalization Angewandte Chemie International Edition 44 3 376 393 doi 10 1002 anie 200300645 PMID 15558637 Schlosser Manfred Strunk Sven 1984 The super basic butyllithium potassium tert butoxide mixture and other lickor reagents Tetrahedron Letters 25 7 741 744 doi 10 1016 s0040 4039 01 80014 9 Benrath Philipp Kaiser Maximilian Limbach Thomas Mondeshki Mihail Klett Jan 2016 08 26 Combining Neopentyllithium with Potassium tert Butoxide Formation of an Alkane Soluble Lochmann Schlosser Superbase Angewandte Chemie International Edition 55 36 10886 10889 doi 10 1002 anie 201602792 ISSN 1521 3773 PMID 27392232 Retrieved from https en wikipedia org w index php title Schlosser 27s base amp oldid 950484207, wikipedia, wiki, book, books, library,
