H-膦酸二苯酯在无水反应条件下发生碱促进的歧化成亚磷酸三苯酯和H-膦酸苯酯。根据31 P NMR数据,提出了这种转化的最可能机理。为了证实这些发现并更深入地了解芳基H-膦酸酯的化学性质,我们还进行了一些有关用各种缩合剂活化苯基和二苯基H-膦酸酯的研究。我们发现,膦酸的芳基对烷基酯通常在活化过程中遵循不同的反应途径,这很可能可以追溯到磷中心的较高亲电性和芳基H-膦酸酯衍生物中PH键的较高反应性。
Radical Cyanation of Alkyl
Iodides with Diethylphosphoryl Cyanide
作者:Sunggak Kim、Chang Cho、Jin Lee
DOI:10.1055/s-0028-1087385
日期:——
The β-elimination of an organophosphoryl group from an iminyl radical is observed for the first time. On the basis of this finding, radical cyanation of alkyl iodides is achieved by using diethylphosphoryl cyanide.
Polyunsaturated Alkyl Amides from Echinacea: Synthesis of Diynes, Enynes, and Dienes
作者:Nicholas J. Matovic、Patricia Y. Hayes、Kerry Penman、Reginald P. Lehmann、James J. De Voss
DOI:10.1021/jo200289f
日期:2011.6.3
constructing alkyl amides containing conjugated diyne and isomerically pure enyne and diene moieties and may be adapted easily for the preparation of other alkyl amides present in Echinacea spp. Terminal-conjugated diynes were prepared by a Cadiot–Chodkiewitz coupling/deprotection sequence utilizing a protected bromoacetylene, and methyl-substituted diynes were made via a base-catalyzed rearrangement of
Phosphonate Modification for a Highly (Z)-Selective Synthesis of Unsaturated Esters by Horner-Wadsworth-Emmons Olefination
作者:Fran�ois P. Touchard
DOI:10.1002/ejoc.200400769
日期:2005.5
The Horner–Wadsworth–Emmons (HWE) reaction of various ethyl diarylphosphonoacetates with benzaldehyde, cyclohexane carboxaldehyde and octanal is reported. Selectivities of up to 98 % at –78 °C are obtained with the three substrates. Among all the phosphonates prepared, the reagent based on 2-tert-butylphenol proved to be especially efficient, with Z/E ratios close to 95:5 at 0 °C. It appears thus to
hate. A number of synthetic routes were explored for the preparation of these targets. The successful approach involved the synthesis of a protected C1–phosphonate ester 17 viaMichaelis–Arbuzovreaction, which was then hydrolysed and coupled with different amino acid esters using aldrithiol. Subsequent hydrogenolysis afforded the targets 2a–g, which were isolated as a mixture of diastereoisomers.
The reaction of enantiomerically enriched 2-methyl-2-nitro-3-(diphenylphosphatoxy)alkyl radicals with tributyltin hydride and AIBN in benzene at reflux results in the formation of alkene radical cation/anion pairs, which are trapped intramolecularly by amine nucleophiles, leading to pyrrolidine and piperidine systems with memory of stereochemistry. The scope and limitations of the system are explored