Electrophilic Fluorination of Secondary Phosphine Oxides and Its Application to P–O Bond Construction

Abstract

A novel and efficient electrophilic fluorination of secondary phosphine oxides with Selectfluor has been achieved. This transformation provides direct access to phosphoric fluorides in up to 92% yield under mild conditions. In addition, P-O bond construction via a one-pot coupling process of secondary phosphine oxides with water or alcohols in the presence of Selectfluor leads to the formation of phosphinic acids or phosphinates in up to 96% yield.

An Efficient Selectfluor-Mediated Oxidative Thio- and Selenocyanation of Diversely Substituted Indoles and Carbazoles

“…Selectfluor,1-chloromethyl-4-fluoro-1,4-diazoniabicyclo-[2.2.2]octane bis(tetrafluoroborate), also known as F-TEDA-BF 4 ) is a safe, bench stable, nontoxic, and highly reactive onium dication salt that delivers an equivalent of electrophilic or radical fluorine [1,2]. For that reason, it is widely used in the synthesis of organofluorine compounds [3][4][5][6][7][8], but it also serves as a versatile catalyst and mediator in transformations involving oxidizable functional groups [9][10][11][12][13].…”

LiI/TBHP Mediated Oxidative Cross‐Coupling of P(O)–H Compounds with Phenols and Various Nucleophiles: Direct Access to the Synthesis of Organophosphates

“…Later, Chen and Han group reported iron catalyzed CDC reaction for the preparation of phosphate esters with P(O)–H compounds and alcohols at high temperature (Scheme c) . Similarly, Chen et al prepared phosphinic acids or phosphinates in the presence of Selectfluor via a one‐pot coupling process of secondary phosphine oxides with water or alcohols (Scheme d) . Recently, Lu group reported an electrophilic phosphination of arenols with diphenylphosphine oxides leading to the formation of diphenyl aryl phosphinates in the presence of Tf 2 O/ H 2 O 2 system (Scheme e) .…”

Fluorination Reaction of P(Ⅲ) Compounds with the Electrophilic Fluorinating Reagent Selectfluor

“…图式 1 有机磷化合物与 Selectfluor 的反应 Scheme 1 Reactions of organophosphorus compounds with Selectfluor 根据我们小组 [10,11] 已有的研究经验, 选取了乙腈/水的 混合溶剂作为反应溶剂. 经过简单的反应条件筛选得到 最优反应条件: 二苯基膦(1a) (0.4 mmol)、Selectfluor (0.52 mmol)、乙腈/水为溶剂, 室温下反应 15 min, 结果 以 79%的收率得到了二苯基磷酰氟 (2a).…”

“…当加入少量或 过量的 Selectfluor 时, 反应过程中仅检测到微量的氧化 产物二苯基氧膦 (3a). 由于 3a 不能迅速地转化为 2a [10] , 因此氟化产物 2a 主要通过 1a 的直接亲电氟化得到. 将 以上反应条件应用于各种三价磷化合物的反应中, 结果 如表 1 所示.…”

“…位阻较大的二芳基氯化膦 1g 和 1h 的氟化反应同样以较 高的收率得到相应的氟化产物 2g 和 2h(表 1, Entries 7, 8), 说明位阻对氯化膦反应的影响较小. 由于二烷基氧 膦与 Selectfluor 的反应效果较差 [10] , 我们进一步尝试了 二环己基氯化膦(1i)的氟化反应, 结果以 66%的收率得 到目标产物 2i(表 1, Entry 9). 另外, 我们还尝试了对水 敏感的二乙基亚磷酰氯(1j)与 Selectfluor 的反应, 结果 原料完全分解, 没有检测到预期的氟化产物(表 1, Entry 10); 当磷原子上带有单个烷氧基时, 甲氧基二苯基膦 (1k)的反应以 70%的收率得到氟化产物 2a 和氧化产物 3k (2a∶3k＝68∶32, 表 1, Entry 11).…”