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1,4‐Addition of TMSCCl 3 to ( E )‐Fumaric Esters and Thermal Rearrangement of the Adducts to 3,4‐Dichloropent‐2‐enedioates
Author(s) -
Wahl Benoit,
Lee Darren S.,
Woodward Simon
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500730
Subject(s) - chemistry , adduct , yield (engineering) , bromide , medicinal chemistry , regioselectivity , catalysis , chloride , organic chemistry , materials science , metallurgy
The diesters ( E )‐RO 2 CCH=CHCO 2 R [R = Et, CH 2 Ph, i Pr, i Bu, t Bu, 2‐ethylhexyl, (–)‐menthyl, (–)‐bornyl] undergo 1,4‐trichloromethylation with Me 3 SiCCl 3 in 84–95 % yield with Bu 4 NX (X = OAc, Cl, F; 0.5–10 mol‐%) as an initiator. Optimal catalysis is attained with X = OAc and F; chloride is less effective, bromide is inadequate. Poor regioselectivity but high yields are demonstrated by mixed diesters (2 examples, both > 80 %). Heating of the trichloromethyl adducts, in the presence of Bu 4 N(OAc), leads to equilibrating, approximately equimolar, mixtures of RO 2 CC(=CCl 2 )CHCO 2 R and RO 2 CCH=CClCHClCO 2 R above 100 °C (7 examples). The latter component is produced under thermodynamic control, which can be isolated pure in some cases. The former is the kinetic product of E2 elimination.