Organic Materials Research Group, Department of Chemistry, Vanderbilt University, Box 1822 Station B, Nashville, TN 37235, USA, phone/fax: (615) 322-3458.
Beilstein J Org Chem. 2011 Mar 31;7:386-93. doi: 10.3762/bjoc.7.49.
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 intermediates in the preparation of liquid crystalline derivatives containing 6-membered heterocyclic rings. Four dibromides 1a-1d containing simple alkyl and more complex fragments at the 3-position were prepared. 3-Propyl- and 3-pentyl-pentane-1,5-diol (2a,b) were prepared starting from either glutaconate or 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.
考察了制备 3-取代-1,5-二溴戊烷 I 及其直接前体的方法，其中包括 3-取代-1,5-戊二醇 VII 或 4-取代四氢吡喃 VIII。这些二溴化物 I 是制备含有 6 元杂环的液晶衍生物的重要中间体。制备了四个含有简单烷基和更复杂片段的 3-位取代的二溴化物 1a-1d。从戊二酸二酯或丙二酸二酯出发，可制备 3-丙基-和 3-戊基-戊烷-1,5-二醇（2a，b），而四氢吡喃 3c 和 3d 则由四氢-4H-吡喃-4-酮得到。讨论了每种路线的优缺点。二溴化物 1c 和 1d 用于制备硫鎓两性离子 11c 和 11d。
