Synthesis of 1,1-difluoroolefins via Wittig-Horner-Emmons reaction

Full text of DOI:10.1080/10426500213415

This article was downloaded by: [McGill University Library]
On: 03 May 2013, At: 11:01
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the Related
Elements
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Synthesis of 1,1-Difluoroolefins Via Wittig-Horner-
Emmons Reaction
Hou-Jen Tsai a
a Chung Cheng Institute of Technology, Republic of China
Published online: 27 Oct 2010.
To cite this article: Hou-Jen Tsai (2002): Synthesis of 1,1-Difluoroolefins Via Wittig-Horner-Emmons Reaction, Phosphorus,
Sulfur, and Silicon and the Related Elements, 177:8-9, 2143-2143
To link to this article: http://dx.doi.org/10.1080/10426500213415
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should
be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,
proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in
connection with or arising out of the use of this material.

Phosphorus, Sulfur and Silicon, 2002, Vol. 177:2143
C
Copyright 2002 Taylor & Francis
1042-6507/02 $12.00 + .00
DOI: 10.1080/10426500290095070
SYNTHESIS OF 1,1-DIFLUOROOLEFINS VIA
WITTIG-HORNER-EMMONS REACTION
Hou-Jen Tsai
Chung Cheng Institute of Technology, Republic of China
(Received July 29, 2001; accepted December 25, 2001)
In the presence of a catalytic amount of cuprous bromide CuBr
and cosolvent acetonitrile acylation of [(diethoxyphosphinyl)diflu-
oromethyl]zinc bromide (EtO)2P(O)CF2ZnBr, which was prepared
from diethyl(bromodifluoromethyl)phosphonate (EtO)2P(O)CF2Br and
zinc powder with an appropriate acylating reagents such as acetyl
chloride CH3C(O)Cl, ethyl oxalyl chloride ClC(O)CO2Et, methyl oxalyl
chloride ClC(O)CO2CH3, diethylcarbamoyl chloride ClC(O)NEt2, or
ethyl chloroformate ClC(O)OEt in the solvent of monoglyme or
triglyme gives diethyl 2-oxo-1,1-difluoropropylphosphonate (EtO)2-
P(O)CF2C(O)CH3, ethyl difluoro(diethoxyphosphinyl)pyruvate (EtO)2-
P(O)CF2C(O)CO2Et, methyl difluoro(diethoxyphosphinyl)pyruvate
(EtO)2P(O)CF2C(O)CO2Me, N,N-diethyl difluoro(diethoxyphosphinyl)
acetamide (EtO)2P(O)CF2C(O)NEt2 and ethyl (diethoxyphosphinyl)
difluoroacetate (EtO)2P(O)CF2C(O)OEt occurs in good yields, respec-
tively. However, in the preparation of (EtO)2P(O)CF2C(O)CO2Et, if
the acylation reaction was carried out at room temperature for 24 h in
the presence of 1.5% of cuprous bromide and without using acetonitrile
as cosolvent, an analogous nerve agent diethyl fluorophosphonate
(EtO)2P(O)F and (EtO)2P(O)CF CFP(O)(OEt)2 were observed. Treat-
ment of a THF solution of diethyl 2-oxo-1,1-difluorophosphonate
derivatives (EtO)2P(O)CF2C(O)R (R CH3, CO2Et, CO2Me, NEt2, OEt)
with Grignard reagents R0MgX via a Wittig-Horner-Emmons reaction
produces 1,1-difluoroolefins R0(CH3)C CF2, R0(CO2Et)C CF2 and
R0(NEt2)C CF2.
Address correspondence to Hou-Jen Tsai, Department of Applied Chemistry, Chung
Cheng Institute of Technology Ta-Hsi, Tao-Yuan, Taiwan, R.O.C.
E-mail: hjtsai@ccit.edu.tw
2143