295-18-1Relevant academic research and scientific papers
Tandem conjugate additions and 3-aza-cope rearrangements of tertiary allyl amines and cyclic α-vinylamines with acetylenic sulfones. Applications to simple and iterative ring expansions leading to medium and large-ring nitrogen heterocycles
Weston, Mitchell H.,Nakajima, Katsumasa,Back, Thomas G.
, p. 4630 - 4637 (2008/09/21)
(Chemical Equation Presented) Tertiary acyclic allyl amines and tertiary cyclic α-vinyl amines undergo conjugate additions to acetylenic sulfones to produce zwitterion intermediates, followed by 3-aza-Cope rearrangements. In the case of cyclic α-vinyl amines, the process results in ring-expansion, providing a novel route to 9- to 17-membered cyclic amines. The Hammett plot for the reaction of 8b with 2a-2f shows ρ = +1.19, which is consistent with formation of the proposed zwitterion in the rate-determining step, where electron-withdrawing substituents on the arylsulfonyl moiety stabilize the negative charge and enhance the rate of the reaction. Alternative pathways were observed in methanol in the case of 11, where a methoxy substituent promotes a dissociative mechanism of the corresponding zwitterion via a stabilized allyl cation, whereas the zwitterion derived from amine 12 undergoes ring-opening by direct attack of methanol upon the strained aziridinium moiety instead of by rearrangement. An iterative process was developed, where the product of one ring-expansion is converted into a new cyclic α-vinyl amine, followed by a repetition of the conjugate addition and [3,3] rearrangement. This protocol was illustrated by its application to the synthesis of motuporamine A and B.
Total synthesis of cytotoxic sponge alkaloids motuporamines A and B
Baldwin, Jack E.,Vollmer, Heidi R.,Lee, Victor
, p. 5401 - 5404 (2007/10/03)
The synthesis of two sponge alkaloids, Motuporamines A and B is reported. The key step involved a reductive amination using sodium triacetoxyborohydride.
Cytotoxic alkaloids motuporamines A-C: synthesis and structural verification.
Goldring,Weiler
, p. 1471 - 1473 (2008/02/09)
[formula: see text] The unusual structure and biological properties of the marine alkaloids motuporamines A-C, as well as the uncertainty as to the position of the olefin within the ring of motuporamine C, led us to synthesize these compounds. The strategy utilized the ring-closing metathesis reaction to form the 14- and 15-membered rings and Michael addition and amidation chemistry to introduce the spermine-like unit. The syntheses, structure assignment verifications, and also the determination of the position of the olefin in motuporamine C are described.
