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The structure of iodolactone 6 was further demonstrated by elimination of HI to form 9, which occurred in hot base10 when KI was added but not without KI addition. This implies that the only proton available for elimination is cis to iodine so that elimination is only effected after initial epimerization of iodide by iodide in an Sn2 displacement. The olefinic lactone 9 produced (bp 140°, 70 µ ) shows only one vinyl proton (t 4.33) in the nmr spectrum, consistent with the assigned structure 9.This synthetic sequence represents a readily available source of perhydroazulenes (25% overall yield to 5, 20% overall to 9) which is applicable to several conversions. Thus, A-bromosuccinimide on 9 affords a single secondary allylic bromide as a route to functionalizing the 5-ring. The typical three-carbon lactone appendages at C-7 in the guaianolide and pseudoguaianolide sesquiterpenes4 are virtually always trans to the C-l hydrogen and so can be stereospecifically introduced via cyclic intermediates from the (cis) carboxyl at C-10. One such procedure could be Claisen condensation of propionate ester with 8, followed by internal displacement of the epoxide by the ß-keto ester anion thus formed.11The perhydroazulenes shown here are presently under investigation for conversion to pseudoguaianolides and conformational analysis models for cycloheptanes.(10) The reaction required 96 hr at 115°in dimethylformamide with diazabicyclooctane (DABCO) as base (yield 91%); higher temperatures caused increasing reversion to acid 5b.(11) The epoxide 8 is very resistant to attack of external nucleophiles, presumably owing to the requisite axial position of the carboxyl at C-10 and the hindrance it offers to backside approach. We have not yet, however, tested the internal displacement.(12) National