After matching the signals sent by the Jedi master, the tremendous trio find that they have not created the desired and necessary intermediate 33! Instead, after examining the signals they determined that 34 was formed!
“Whhhaaahghahhagaghghgh?” (“why” in wookie) asks Chew-Bowman. All three stop to wonder and realize they cannot figure this out by themselves. They head to the 3rd floor of the Coruscant Public Science Library and spend three days on SciFinder Scholar trying to find an explanation for their unexpected results.
They are still at a loss.
Li, T.T.; Lesko, P.; Ellison, R. H.; Subramanian, N.; Fried, J. H. J. Org. Chem. 1981, 46, 111-115.
In this study, Li and et al. attempt to find a novel and more facile method of synthesizing an α,β-unsaturated aldehyde important to the synthesis of multiple prostaglandins. Present syntheses are based on the transformation of a Corey lactone intermediate. In one attempt to control regioselective addition of a carbon atom at one end of the double bond in the ene-lactone intermediate in this reaction scheme, they propose the activation of an orthoformate with an acid to promote an attack of the double bond. Instead, the double bond of the resonance stabilized intermediate attacks at an electrophilic center. This article was cited by Frontier and et al. to come up with an alternate procedure from 32a to lactone 34: degradation of alternate chloroformate 35 and orthoester 36 to highly reactive oxonium ions, which could then react as proposed in the failed step.
Reference 1:
Vionnet, J. P.; Renaud, P. Helv. Chim. Acta. 1994, 77, 1781-1790.
The authors of this article report a facile and stereoselective synthesis of an all cis-formyllactone, related to Corey lactone, from the radical addition-acyl migration of an intermediate. Acetyl hydrolization and lactonization reagents (H2O2/ acetone and PPTS/CHCl3, respectively) are employed to convert their beginning product to the cis-formyllactone. Their all cis-formyllactone is filtrated through silica gel to get a product that is compared with the α,β-unsaturated aldehyde that is created from Li and et al.’s experimental. The Corey lactone can be seen as an analog of the Frontier article lactone 33. Frontier and et al. draw from the information presented in attempts to synthesize their own lactone after their first scheme fails.
Reference 2:
Esch, P. M.; de Boer F., R.; Hiemstra, H.; Ilona M., B.; Speckamp, W. N. Tetrahedron. 1991, 47, 4063-4076.
This work focuses on cyclization reactions of acylic iminium ions. They show that previous works have used formic acid to bring about cyclization of N-acyliminium ions from N-substituted succinimides. The authors have previously studied Lewis acid-induced cyclization of the acylic iminium ions before. Little examples of formic acid-induced cyclization with the alkene as a nucleophile have been done before, so they use the knowledge from Li and et al.’s paper (one of the few who have achieved this before). Correct cyclization of all of these articles is key; as Frontier and et al. failed to produce the right lactone intermediate of their study.
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