Categories: C=C Bond Formation >
Synthesis of terminal olefins
Name Reactions
More general methods can be found here.
Recent Literature
1-methyl-2-(methylsulfonyl)benzimidazole reacts with a variety of aldehydes and
ketones in the presence of either NaHMDS (-55 °C to rt) or t-BuOK (rt, 1
h) in DMF to give the corresponding terminal alkenes in high yields. The
byproducts of this Julia-type methylenation reagent are easily removed, and the
reaction conditions are mild and practical.
K. Ando, T. Kobayashi, N. Uchida, Org. Lett.,
2015,
17, 2554-2557.
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.
A mechanistically distinct tactic to carry E2-type eliminations on
alkyl halides is based on the interplay of α-aminoalkyl radical-mediated
halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology
is high-yielding and tolerates many functionalities. Fine-tuning of the
electronic and steric properties of the cobalt catalyst provides high olefin
positional selectivity.
H. Zhao, A. J. McMillan, T. Constantin, R. C. Mykura, F. Juliá, D. Leonori, J. Am. Chem. Soc.,
2021, 143, 14646-14656.
Brønsted Acid Catalyzed Peterson Olefinations
T. K. Britten, N. G. McLaughlin, J. Org. Chem., 2020, 84,
301-305.
The bidentate phosphine DPPM mediates an efficient methylenation of acyl fluorides and
acyl chlorides substituted with aryl, alkenyl, and alkyl groups with
trimethylaluminum to provide various 2-substituted propene derivatives.
X. Wang, Z. Wang, Y. Asanuma, Y. Nishihara,
Org. Lett., 2019, 21, 3640-3643.
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.
A transformation of aldehydes into terminal olefins through reduction of the
corresponding enol triflates is effective with both linear and α-branched
aldehydes.
S. K. Pandey, A. E. Greene, J.-F. Poisson, J. Org. Chem.,
2007,
72, 7769-7770.
A stepwise PCET activation of thermodynamically stable olefins is mediated by
an excited-state oxidant and a Brønsted base to afford an allylic radical that
is captured by a Cr(II) cocatalyst to furnish an allylchromium(III) intermediate.
In situ protodemetalation of this allylchromium complex by methanol is highly
regioselective and affords an isomerized and less thermodynamically stable
alkene product.
K. Zhao, R. R. Knowles, J. Am. Chem. Soc.,
2022, 144, 137-144.
β-Hydride elimination, an undesired elementary step in palladium-catalyzed
cross-coupling reactions, allows dehydrohalogenations of alkyl bromides to form
terminal olefins in excellent yield at room temperature in the presence of
various functional groups.
A. C. Bissember, A. Levina, G. C. Fu, J. Am. Chem. Soc., 2012,
134, 14232-14237.
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.
A Rh-catalyzed dehomologation of primary alcohols enables the synthesis of
olefins via an oxidation-dehydroformylation sequence in the presence of N,N-dimethylacrylamide
as hydrogen acceptor. Alcohols with diverse functionality and structure undergo
oxidative dehydroxymethylation to access the corresponding olefins.
X. Wu, F. A. Cruz, A. Lu, V. M. Dong, J. Am. Chem. Soc.,
2018,
140, 10126-10130.
In the presence of a 1:1 mixture of n-butyllithium and lithioacetonitrile
in THF, a series of styrene oxides can be converted into one-carbon homologated
allyl alcohols in an unusual regioselective manner.
T. Tomioka, R. Sankranti, T. Yamada, C. Clark, Org. Lett., 2013,
15, 5099-5101.
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.
Regioselective C-C bond fragmentation of cyclopropanes followed by
desulfonylation enables a one-step strategy for the synthesis of α-methenyl
ketones from β-keto sufones. Success of the methodology is elaborated for the
synthesis of chromanones and isoflavanones in one-step.
G. Pandey, J. Vaitla, Org. Lett.,
2015,
17, 4890-4893.
The application of the 1-butyl-3-methylimidazolium-based ionic liquid [BMIM][NTf2]
as solvent enabled clean α-methylenations of carbonyl compounds in a short time
and good yields. This ionic liquid was reused without affecting the reaction
rates or yields over seven runs.
J. A. Vale, D. F. Zanchetta, P. J. S. Moran, J. A. R. Rodrigues, Synlett, 2009,
75-78.
Various aryl ketone derivatives react readily with DMSO under transition
metal-free reaction condition, producing the α,β-unsaturated carbonyl compounds
in good yields. This direct α-Csp3-H methylenation offers wide
substrate scope and provides an efficient and expeditious approach to an
important class of α,β-unsaturated carbonyl compounds.
Y.-F. Liu, P. Yi Ji, J.-W. Xu, Y.-Q. Hu, Q. Liu, W.-P. Luo, C.-C. Guo, J. Org. Chem.,
2017, 82, 7161-7164.
Gold catalysis enables a chemoselective α-methylenation of aromatic ketones
using Selectfluor as a methylenating agent to provide various 1,2-disubstituted
propenone derivatives in good yields. This reaction offers simple operation,
good functional group tolerance, and broad scope of substrates.
H. Zhu, X. Meng, Y. Zhang, G. Chen, Z. Cao, X. Sun, J. You, J. Org. Chem.,
2017, 82, 12059-12065.
An expeditious synthesis of α-substituted tert-butyl acrylates from
commercially available aldehydes and Meldrum's acid includes a telescoped
condensation-reduction sequence to afford 5-monosubstituted Meldrum's acid
derivatives followed by a Mannich-type reaction triggered by a rapid
cycloreversion of the dioxinone ring on heating with tert-butyl alcohol.
C. G. Frost, S. D. Penrose, R. Gleave, Synthesis, 2009,
627-635.
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