Opekar Stanislav, Pohl Radek, Beran Pavel, Rulíšek Lubomír, Beier Petr
Chemistry. 2014 Jan 27;20(5):1453-8. doi: 10.1002/chem.201303817.
Diethyl fluoronitromethylphosphonate (3), a previously unknown compound, was synthesized by electrophilic fluorination of diethyl nitromethylphosphonate with Selectfluor. Base-induced decomposition of 3 was studied by NMR spectroscopy, which identified diethyl fluorophosphate and fluoronitromethane as the main decomposition products. C-H acidities [pK(a) values in dimethyl sulfoxide (DMSO)] of 3, 1-fluoro-1-phenylsulfonylmethanephosphonate (1; McCarthy's reagent), tetraethyl fluoromethylenebisphosphonate (2), and some nonfluorinated phosphonates were computed, and a good correlation between calculated and experimental pK(a) values was found. The calculated C-H acidities increased in the sequence 2<1<3. Diethyl fluoronitromethylphosphonate (3) was applied in the Horner-Wadsworth-Emmons reaction with aldehydes and trifluoromethyl ketones to provide new 1-fluoro-1-nitroalkenes with good to high stereoselectivities. Alkylation of 3 was successful only with iodomethane, however, conjugate additions of 3 to Michael acceptors such as α,β-unsaturated carbonyl compounds, sulfones, and nitro compounds allowed access to variously modified diethyl 1-fluoro-1-nitrophosphonates.
二乙基亚硝基甲基膦酸酯（3）是一种此前未知的化合物，通过用Selectfluor对二乙基亚硝基甲基膦酸酯进行亲电氟化反应合成得到。利用核磁共振光谱对3的碱诱导分解进行了研究，结果确定二乙基氟磷酸酯和氟硝基甲烷为主要分解产物。计算了3、1-氟-1-苯基磺酰基甲烷膦酸酯（1；麦卡锡试剂）、四乙基氟亚甲基双膦酸酯（2）以及一些非氟化膦酸酯的C-H酸度[在二甲亚砜（DMSO）中的pKa值]，发现计算得到的pKa值与实验值之间具有良好的相关性。计算得到的C-H酸度按2<1<3的顺序增加。二乙基亚硝基甲基膦酸酯（3）用于与醛和三氟甲基酮进行霍纳-沃兹沃思-埃蒙斯反应，以提供具有良好至高立体选择性的新型1-氟-1-硝基烯烃。然而，3仅与碘甲烷的烷基化反应成功，而3与迈克尔受体（如α,β-不饱和羰基化合物、砜和硝基化合物）的共轭加成反应则可得到各种修饰的二乙基1-氟-1-硝基膦酸酯。
