Aza-Brook rearrangement

In a study designed to test the feasibility of a germanium aza Brook rearrangement, the /V-benzyl derivative 25 of amine 24 was treated with BuLi13. After subsequent addition of water, the hydride 28 was obtained as the sole Ge-containing product (Scheme 11). 

What is known as the aza-Brook rearrangement deals uniquely with monosubstituted MSMAs. When it was reported for the first time that n-butyllithium reacted with excess A-trimethylsilylmethyl-n-butylamine to yield A-methyl-n-butylamine, it was assumed that the intermediate lithium amide underwent a metal exchange.324... 

Liu, G., Sieburth, S. M. Enantioselective a-Silyl Amino Acid Synthesis by Reverse-Aza-Brook Rearrangement. Org. Lett. 2003, 5,4677-4679. 

Aza-Brook rearrangement. (a-Silylallyl)amines undergo the rearrangement to rmerate the functionalized allyl anions, which, on alkylation and acid hydrolysis, lead to. ..nstituted aldehydes. 

Rearrangements. The reverse aza-Brook rearrangement of Boc-protected A -silylamines gives a-amino silanes. In the presence of (—)-sparteine, this reaction leads to products in high yields and >90% ee and may be carried out using allyl-, benzyl-, or propagylamines (e.g., eq 65). 

Gandon, V., Bertus, P., Szymoniak, J. New transformations from a 3-silyloxy-2-aza-1,3-diene consecutive Zr-mediated retro-Brook rearrangement and reactions with electrophiles. Tetrahedron 2000, 56, 4467-4472. 

One of the most used sequential component reactions in the asymmetric construction of chiral compounds is the so-called anion relay chemistry (ARC) [2], This linchpin coupling protocol consists in the alkylation of an anion, generally a silyl lithium dithiane derivative, by an epoxide or an aziridine, resulting in an oxy- or aza-anion, which in the presence of hexamethylphosphoramide (HMPA) or other polar solvent gives a 1,4-Brook rearrangement, thereby leading to a new reactive dithiane anion that is capable of reacting with a second electrophile E+ (Scheme 11.1). 

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