The preparation of 3-substituted-1,5-dibromopentanes as precursors to heteracyclohexanes

• Bryan Ringstrand,
• Martin Oltmanns,
• Jeffrey A. Batt,
• Aleksandra Jankowiak,
• Richard P. Denicola and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2011, 7, 386–393, doi:10.3762/bjoc.7.49

• Łódź, Tamka 12, 91403 Łódź, Poland 10.3762/bjoc.7.49 Abstract The methodology to prepare 3-substituted 1,5-dibromopentanes I and their immediate precursors, which include 3-substituted 1,5-pentanediols VII or 4-substituted tetrahydropyrans VIII, is surveyed. Such dibromides I are important

• malonate diesters, while tetrahydropyrans 3c and 3d were obtained from tetrahydro-4H-pyran-4-one. The advantages and disadvantages of each route are discussed. Dibromides 1c and 1d were used to prepare sulfonium zwitterions 11c and 11d. Keywords: 1,5-dibromopentanes; heterocycles; methodology; synthesis

• ; Introduction 3-Substituted 1,5-dibromopentanes I and disulfonates, typically tosylates II, serve as useful intermediates in the preparation of six-membered heterocycles such as 4-substituted-piperidines III, thianes IV, silacyclohexanes V, and phosphorinanes VI (Figure 1). The piperidines III (Y = Ar) have