Tan Jin-Fay, Bormann Carl Thomas, Severin Kay, Cramer Nicolai
Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305 CH-1015 Lausanne Switzerland
Laboratory of Supramolecular Chemistry, EPFL SB ISIC LCS, BCH 3307 CH-1015 Lausanne Switzerland.
Chem Sci. 2022 Feb 9;13(12):3409-3415. doi: 10.1039/d2sc00294a. eCollection 2022 Mar 24.
The 1,1,2,2-tetrafluoroethylene unit is prevalent in bioactive molecules and functional materials. Despite being in principle a straightforward strategy to access this motif, the direct tetrafluorination of alkynes involves very hazardous or inconvenient reagents. Therefore, safer and convenient alternatives are sought after. We developed a mild and operationally simple perfluorination method converting 1-alkynyl triazenes into 1,1,2,2-tetrafluoro alkyl triazenes, employing cheap and readily accessible reagents. Moreover, a judicious tuning of the reaction conditions enables access to α-difluoro triazenyl ketones. Complementary, electrophilic fluorination of alkynyl triazenes gives rise to the regioisomeric α-difluoro acyl triazenes. These three chemo- and regio-divergent protocols enable access to elusive fluorinated 1-alkyl and 1-acyl triazenes, thus expanding the chemical space for these unusual entities. Furthermore, several reaction intermediates and side products revealed insights on the reaction pathways that may be useful for further fluorination chemistry of alkynes.
1,1,2,2-四氟乙烯单元在生物活性分子和功能材料中普遍存在。尽管从原则上讲，获取该结构单元是一种直接的策略，但炔烃的直接四氟化涉及非常危险或不便的试剂。因此，人们一直在寻找更安全、更方便的替代方法。我们开发了一种温和且操作简单的全氟化方法，使用廉价且易于获得的试剂将1-炔基三氮烯转化为1,1,2,2-四氟烷基三氮烯。此外，通过合理调整反应条件能够得到α-二氟三氮烯基酮。作为补充，炔基三氮烯的亲电氟化会生成区域异构体α-二氟酰基三氮烯。这三种化学和区域发散的方法能够合成难以捉摸的氟化1-烷基和1-酰基三氮烯，从而扩展了这些特殊物质的化学空间。此外，几种反应中间体和副产物揭示了反应途径的相关信息，这可能对炔烃的进一步氟化化学有用。
