1126-19-8Relevant academic research and scientific papers
A Schmidt route to 1-azabicyclo[x.y.0]alkanes: A comparison of carbocation stabilizing groups
Pearson, William H,Walavalkar, Rajesh
, p. 5081 - 5089 (2007/10/03)
The intramolecular Schmidt reactions of tertiary alkyl, tertiary benzylic, tertiary propargylic, and tertiary allylic carbocations with tethered azides are reported. Using product analysis and deuterium labeling studies, the role of cation rearrangement p
Azidomercurations of alkenes: Mercury-promoted Schmidt reactions
Pearson,Hutta,Fang
, p. 8326 - 8332 (2007/10/03)
Azides bearing a suitably disposed alkene, when treated with either mercuric perchlorate or mercuric trifluoromethanesulfonate, produce bicyclic iminium ions. This new version of the Schmidt reaction proceeds by capture of the mercuronium ion intermediate by the azide to produce an aminodiazonium ion, which suffers a 1,2-shift to give an iminium ion (e.g., 10 → 16 → 17 → 18). Reduction of the iminium ion may then be carried out to produce an amine. Compared to earlier work on the protic acid-promoted intramolecular Schmidt reaction of azido-alkenes, the mercury-promoted Schmidt reaction has several advantages. First, the acid-promoted Schmidt reaction of azido-alkenes requires that the intermediate carbocations be tertiary, allylic, benzylic, or propargylic. The mercury-promoted method has no such limitation; thus even 1,2-disubstituted alkenes may be used. Second, the mercury-promoted method is milder, allowing the presence of acid-sensitive functionality. The protic version, typically employing trifluoromethanesulfonic acid, is limited in its functional group tolerance. Third, whereas carbocation rearrangement is often observed prior to cyclization/rearrangement in the acid-promoted Schmidt reaction, the mercury-promoted method avoids this problem. Fourth, the presence of the mercurio group during the rearrangment may alter the regioselectivity of the 1,2-migration. Finally, the mercury-bearing iminium ions that are the result of the Schmidt reaction were found to be sensitive to protodemercuration, precluding their use in other transformations.
Intramolecular Schmidt reactions of alkyl azides with ketones: Scope and stereochemical studies
Milligan, Gregory L.,Mossman, Craig J.,Aubé, Jeffrey
, p. 10449 - 10459 (2007/10/03)
The intramolecular Schmidt reaction of alkyl azides and ketones has been demonstrated. The reaction is proposed to occur via initial attack of an azide on a ketone activated by a variety of protic or Lewis acids, including trifluoroacetic acid, titanium tetrachloride, and others. The resulting azidohydrin undergoes a direct rearrangement to afford the product amide and molecular nitrogen. When cyclic ketones are used, fused bicyclic lactams of types encountered in a wide variety of natural products are obtained. Although the distance allowed between the carbonyl group and the alkyl azide is quite restricted, the reaction is general with respect to the ketone component, including acyclic ketones and cyclic substrates ranging from standard to large ring sizes. The reaction also succeeds with aldehydes, although elimination or hydride migration products compete. In several cases examined the reaction was found to proceed with retention of configuration at the migrating carbon. Competing reactions with β-diketones and α,β-unsaturated ketones were found to predominate over ring expansion.
Synthesis and Thermolysis of O-Alkyl-N-vinylhydroxylamine Derivatives
Shatzmiller, Shimon,Shalom, Eytan
, p. 897 - 905 (2007/10/02)
Oxoiminium salts 11 a-e and 13 a-e have been prepared from the ο-chloroketones 9 a-e by oximation via the cyclic oxime ethers 10 a-e and the cyclic imine oxides 12 a-e, followed by alkylation with "Meerwein salt".The deprotonation reaction of 11 a-e and 13 a-e yields, via the regioselectively prepared intermediates 14 a-e and 17 a-e, the α, β-unsaturated imines 15 a-e and the cyclic imines 18 a-e, respectively.
