Azaphilic versus Carbophilic Coupling at CN Bonds: Key Steps in Titanium‐Assisted Multicomponent Reactions |
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Authors: | Torsten Roth Prof. Hubert Wadepohl Dr. Eric Clot Prof. Lutz H. Gade |
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Affiliation: | 1. Anorganisch‐Chemisches Institut, Universit?t Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany);2. Institut Charles Gerhardt, CNRS 5253, cc 1501, Université de Montpellier, Place Eugène Bataillon, 34000 Montpellier (France) |
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Abstract: | Consecutive C‐ and N‐arylation of N‐heterocyclic nitriles is mediated by titanium(IV) alkoxides. The carbo‐ and azaphilic arylation step may be separated by choosing the order in which the two equivalents of aryl transfer reagent are added. In the course of this transformation, the ancillary N‐heterocycle acts as both a directing anchor group and electron reservoir. In the selectivity‐determining step, the selectivity is governed by a choice between (direct) C‐ and Ti‐arylation; the latter opens up a reaction pathway that allows further migration to the nitrogen atom. The isolation of metal‐containing aggregates from the reaction mixture and computational studies gave insights into the reaction mechanism. Subsequently, a multicomponent one‐pot protocol was devised to rapidly access complex quaternary carbon centers. |
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Keywords: | heterocycles metallacycles multicomponent reactions synthetic methods titanium |
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