diisopropylamine has been shown to influence reaction product distributions,1011'' to the best of our knowledge, this is the first systematic study proving that HMDS is free in solution prior to and after completion of an aldol reaction. Previously, it had been assumed that the steric bulk of HMDS prevented it from interacting with the enolate.The influence of counterion effects was probed by the reaction of sodium, potassium, and cryptated-potassium pincolonates with pivalaldehyde. The non-lithium aldolate products were found to undergo elimination after several seconds, making the analogous structural and calorimetric investigations impossible, and emphasizing yet again the important role of lithium in these reactions. ConclusionsIn order to study even the simplest aldol reaction in nonpolar media systematically, it is necessary to apply a methodology that employs a variety of methods to elucidate the structures of the reactants and products, thermochemical measurements, and, ultimately, kinetic studies. Excluding kinetics, we have successfully applied this methodology to yield the first concrete structure-Synthesis of (-)-Brevianamide B Chart I Scheme I 6, L-TRP-L-PRO 7 ,brevianam.de F),deoxybrev.anam.de e, arrangement of 9 is well-precedented7 8 to afford the spiro indoxyl system, via the 3-hydroxyindolenine 10 (Scheme I).The brevianamides are members of a curious, yet growing, small class of mycotoxins that has recently been joined by marcfortine9 (11) and paraherquamide10 (12), which has now been shown to (7) Experimental support for this hypothesis has been realized in a model reaction: (a)

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