Categories: C=C Bond Formation >
Synthesis of terminal olefins
Name Reactions
More general methods can be found here.
Recent Literature
The methylenation of aldehydes and ketones under optimized Julia-Kocienski
conditions was conducted by using 1-tert-butyl-1H-tetrazol-5-ylmethyl
sulfone with either NaHMDS at -78°C or Cs2CO3 at 70°C.
The latter conditions are also adapted for the preparation of
1,2-disubstituted olefins and intramolecular olefinations.
C. Aïssa, J. Org. Chem.,
2006, 71, 360-363.
C. Aïssa, J. Org. Chem.,
2006, 71, 360-363.
Inexpensive (NHC)-Cu complexes efficiently catalyzed the methylenation of
various aliphatic and aromatic carbonyl compounds in the presence of
trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. High yields were
obtained for the formation of styrenes containing nitro, trifluoromethyl, amino,
and ester groups.
H. Lebel, M. Davi, S. Díez-Gonzlez, S. P. Nolan, J. Org. Chem., 2007,
72, 144-149.
A mild and nonbasic rhodium-catalyzed methylenation of aldehydes using
trimethylsilyldiazomethane and triphenylphosphine in THF produces various
terminal alkenes in excellent yields including enolizable keto aldehydes and
nonracemic aldehydes. The use of an easily removable phosphine is also
described.
H. Lebel, V. Paquet, J. Am. Chem. Soc.,
2004, 126, 320-328.
An oxidation-methylenation one-pot procedure in the presence different
catalysts produced terminal alkenes in high yields. A
methylenation-ring-closing process for the synthesis of cyclic alkenes from
carbonyl derivatives was even expanded with an initial oxidation to allow
the use of alcohols as substrates.
H. Lebel, V. Paquet, J. Am. Chem. Soc.,
2004, 126, 11152-11153.
Heating with NaI and DBU in dimethoxyethane effected clean
elimination of tosylates to terminal olefins. This simple one-pot procedure was
also applied to tosylates derived from an Evans Aldol Reaction.
P. Phukan, M. Bauer, M. E. Maier, Synthesis, 2003, 1324-1328.
The preparation of any length alkenyl halide from inexpensive starting
reagents is reported. Standard organic transformations were used to prepare
straight chain α-olefin halides in excellent overall yields with no
detectable olefin isomerization and full recovery of any unreacted starting
material.
T. W. Baughman, J. C. Sworen, K. B. Wagener, Tetrahedron, 2004, 60, 10943-10948.
Two optimal catalytic systems for the convenient and fast α-methylenation of
aldehydes with aqueous formaldehyde are described that allow short reaction
times and afford the methylenated products in good to excellent yields and
chemoselectivity.
A. Erkkilä, P. M. Pihko, J. Org. Chem., 2006, 71, 2538-2541.
| Related:
|
