[English name] (1,3-dioxolan-2-ylmethyl) triphenylphosphinium bromide
[Formula] c22h22bro2p
[molecular weight] 429.29
[Ca login No.] [52509-14-5]
[physical properties] MP 193 ~ 195 OC.
[preparation and commodity] the reagent is prepared by reacting triphenylphosphine with 2-bromomethyl-1,3-dioxolane at 100 OC for 36 h [1]. The commercial reagent is 98% white solid.
[note] the reagent decomposes with acid.
--------------------------------------------------------
(1,3-dioxopenyl-2-yl) methyltriphenylphosphonium bromide is a reagent used to form carbon skeleton. It can be used in Wittig alkylation and synthesis of α, β - unsaturated aldehydes.
The phosphorus salt can react with alkali to form (1,3-dioxaphentane-2-methylene) triphenylphosphine. This phosphorus ylide reacts with aldehyde to obtain α, β - unsaturated glycol acetal. The corresponding aldehyde (formula 1) [2] is obtained by acid hydrolysis. The stereochemistry of the double bond in the acetal product is greatly affected by alkali or solvent.
In the DMSO solution of sodium hydride, formula 2 reacts with (1,3-dioxolane-2-yl) methyltriphenylphosphonium bromide, and the ratio of z-and e-acetals is 3:1; when THF is added to the system, the ratio of z-and e-products can reach 7:1 (formula 2) [3 ~ 5]. When reacting in thf-hmpa solution of sodium hydride, the main Z-configuration product (formula 3) is obtained.
Due to the isomerization at the same time of acid catalyzed hydrolysis, the α, β - unsaturated aldehydes obtained are mainly of e-type configuration. In THF, it is one of the most commonly used methods (formula 4, formula 5) [6,7] to synthesize α, β - unsaturated aldehydes with two more carbon atoms than the original carbon frame by the reaction of phosphorus salt and tert butyl potassium in-situ formed phosphorus ylide with aldehydes and then hydrolysis under the action of acid.
Active alcohols such as benzyl alcohol can be directly oxidized Wittig reaction in THF with the mixture of manganese dioxide and organic base mtbd, and then hydrolyzed with acid to obtain high yield α, β - unsaturated aldehydes (formula 6) [8]. Due to the isomerization in the hydrolysis process, the final product is mainly stable e-configuration. The reactivity of the salt with ylide and ketone formed by alkali is usually low.
reference
1. Cresp, T. M.; Sargent, M. V.; Vogel, P. J. Chem. Soc., 1974, 37.
2. Ojima, J.; Ejiri, E.; Kato, T.; Kuroda, S.; Hirooka, S.; Shibutani, M. Tetrahedron Lett., 1986, 27, 2467.
3. Fraser-Reid, B.; Molino, B. F.; Magdzinski, L.; Mootoo, D. R. J. Org. Chem., 1987, 52, 4505.
4. Fraser-Reid, B.; Magdzinski, L.; Molino, B. F.; J. Am. Chem. Soc., 1984, 106, 731.
5. Daniewski, A. R.; Wojceichowska, W. J. Org. Chem., 1982, 47, 2993.
6. Hopf, H.; Krüger, A. Chem. Eur. J., 2001, 7, 4378.
7. Hopf, H.; Greiving, H.; Beck, C.; Dix, I.; Jones, P. G.; Desvergne, J.-P.; Bouas-Laurent, H. Eur. J. Org. Chem., 2005, 567.
8. Reid, M.; Roweb, D. J.; Taylor, R. J. K. Chem. Commun., 2003, 2284.
This paper is from: modern organic synthetic reagents -- properties, preparation and reaction, edited by Hu Yuefei, et al