@article{08bce085d7b0412a811eebda95cbb719,
title = "Intramolecular azide cycloaddition (IAC) reactions in the indole series - an approach to clavicipitic acid",
abstract = "The intramolecular [3+2] cycloaddition of azide to olefin has been explored as a possible route to the structurally unique alkaloid clavicipitic acid.",
author = "Kozikowski, {Alan P.} and Greco, {Michael N.}",
note = "Funding Information: The directionality of the initial [3+21 dipolar cycloaddltion reaction of 2 can be understood -in part on the basis of the perhaps outmoded, but nonetheless predictrve formalism of Euisgen6 in which the unsubstltuted nitrogen of the azide is considered to be electrophilic and the Internal nitrogen nucleophilic in character. The carbon atom of the olefin nearest the indole ring might best be able to accommodate some partial positive charge character. More importantly, however, the geometric and steric constraints for cycloaddition are such that formation of the other regioisomer (especially in the case of the cis olefin) appears prohibitive (see Dreading models). These latter factors can, of course, completely dominate the aforementioned resonance considerations (or calculated HOMO/LUMOi nteractions). In summary, we believe that the work reported herein does offer a reasonable route to clavicipitic acid and its analogues. The use of a more highly functionalized Wittig reagent in the opening step of the synthesis, or the introduction of additional functionality into 2 through utilization of the activating effect of the imine functional group should make it possible to synthesize the parent structure J.7,0 Acknowledgements. We are indebted to the National Institutes (Grant No. HL-20579) and the Camille and Henry Dreyfus Foundation, support of these investigations. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.",
year = "1982",
doi = "10.1016/S0040-4039(00)87245-7",
language = "English (US)",
volume = "23",
pages = "2005--2008",
journal = "Tetrahedron Letters",
issn = "0040-4039",
publisher = "Elsevier Limited",
number = "19",
}