Selenium--Stabilized Anions. Preparation of α,β-Unsaturated Carbonyl Compounds Using Propargyl Selenides. Synthesis of (+/-)-7-Hydroxymyoporone

Article abstract of DOI:10.1021/ja00401a032

The reaction of alkyl halides, carbonyl compounds, and trimethylsilyl chloride with the mono- and dianion (1) prepared by deprotonation of phenyl propargyl selenide with lithium diisopropylamide gives 1- or 3-monosubstituted or 1,3-disubstituted propargyl selenides (3a).Oxidation to selenoxides (3b) results in rearrangement to 2-(phenylseleno)-1,3-disubstituted propenones.The rate of rearrangement of propargyl selenoxides increases dramatically when the phenyl group is replaced by a 2-nitrophenyl group, and an intermediate allenyl selenate ester (7c) can be observed by low-temperature NMR.By appropriate modification of oxidation conditions, modest yields of 2-iodopropenes (e.g., 10) or the selenium-free enones or enals can be obtained.A synthesis of (+/-)-7-hydroxymyoporone (15) and its epimer has been carried out by using the dianion 1 to assemble the carbon skeleton.The preparation of α-lithioallenyl phenyl selenide (26) has been accomplished, and its reaction with electrophiles has been studied.