Sulfur-Mediated Rearrangements I

In their analysis of experiments and in their planning of syntheses, organic chemistsconsciouslyorunconsciouslytendtousetheprincipleofleastmotion, thechemicalequivalentofOccam'srazor. Inrearrangementreactionsthispr- ciple is violated and may make rearrangements problematic reactions. At the sametime,thereisalwaysfascinationintheunexpectedandsorearrangement reactionsarealsoanattractive'eldofstudy. Consequently, ourunderstanding of rearrangement reactions is now quite advanced and allows strategic uses in organic synthesis. Here, a helpful tool that may easily be overlooked is thein'uence oforganosulfurfunctionalitiesontheserearrangements. Infact, the presence of sulfur may make rearrangements predictable and productive or allow speci'c transformations which would otherwise require a tedious synthetic detour. The present account is meant to spread this knowledge. In addition, an introductory chapter gives a survey of the basics of organosulfur chemistry to put the information in the individual chapters into perspective and to help readers who are less familiar with the peculiarities of sulfur in an organicenvironment. Theamountofmaterialrequiringcoveragewassovastthatthevolumehadto besplitintotwoparts. Wehopethatreaderswillappreciatethecomprehensive and up-to-date information on sulfur-mediated rearrangements. Fortunately, leading experts were available to write the individual chapters and provide state-of-the-artreviews ofthecurrent researchonsulfur-mediated rearran- ments. It was a pleasure to work with these colleagues and I appreciate their involvement in spite of many other obligations. This volume should help the chemical community in their synthetic workand so it was worththe effort. Clausthal-Zellerfeld, October 2006 Ernst Schaumann Contents SulfurisMoreThantheFatBrotherofOxygen. AnOverviewofOrganosulfurChemistry E. Schaumann. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 RecentAdvancesinPummererReactions S. Akai·Y. Kita . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 1,2-SulfurMigrations A. W. Sromek·V. Gevorgyan. . . . . . . . . . . . . . . . . . . . . . . . 77 1,3-SulfurShifts:MechanismandSyntheticUtility S. K. Bur. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 AuthorIndexVolumes251-274. . . . . . . . . . . . . . . . . . . . . . 173 Subject Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 ContentsofVolume275 Sulfur-MediatedRearrangementsII Volume Editor: Ernst Schaumann ISBN: 978-3-540-68099-4 [2,3]-Sigmatropic RearrangementsofAllylic Sulfur Compounds M. Reggelin [2,3]Sigmatropic RearrangementsofPropargylic andAllenicSystems S. Braverman ·M.