Categories: C=C Bond Formation >
Synthesis of alkenes by anti-eliminations
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.
The use of SmI2 in the reductive elimination of 1,2-acetoxy sulfones (Julia-Lythgoe olefination) and the reductive cleavage of vinyl sulfones is reported.
G. E. Keck, K. A. Savin, M. Weglarz, J. Org. Chem., 1995, 60, 3194-3204.
Samarium diiodide promotes a photoinduced metalation of nonactivated C-Cl bonds of O-acetyl chlorohydrins and a β-elimination which affords alkenes with total or high stereoselectivity.
J. M. Concellón, H. Rodriguez-Solla, C. Simal, M. Huerta, Org. Lett., 2005, 7, 5833-5835.
A microwave-assisted, metal-free direct decarboxylative elimination of arylacetic acids in the presence of PIFA as oxidant readily provides alkenes in good yields.
S.-W. Wu, J.-L. Liu, F. Liu, Org. Lett., 2016, 18, 1-3.
The use of TMSO-/Bu4N+ as Lewis base activator enables highly stereoselective aza-Peterson olefinations from bench-stable α,α-bis(trimethylsilyl)toluene reagents and N-substituted imines. N-t-butanesulfinyl imines were utilized for the synthesis of Z-stilbenes with excellent selectivities, while N-aryl imines generated E-stilbenes under identical reaction conditions via syn-elimination of an in situ formed hypervalent silicate.
M. Das, D. F. O'Shea, Org. Lett., 2016, 18, 336-339.
A samarium-promoted synthesis of (E)-nitroalkenes from 1-bromo-1-nitroalkan-2-ols in high yields together with an efficient preparation of the 1-bromo-1-nitroalkan-2-ols constitutes a simple and advantageous alternative toward nitroalkenes with total E-stereoselectivity. A mechanism is proposed to explain the E-stereoselectivity of the β-elimination reaction.
J. M. Concellón, P. L. Bernad, H. Rodríguez-Solla, C. Concellón, J. Org. Chem., 2007, 72, 5451-5423.
A zinc carbenoid-mediated chain extension of β-dicarbonyl compounds provides access to α,β-unsaturated-γ-keto esters and amides with complete E selectivity via an intermediate zinc enolate, which is treated sequentially with iodine and DBU.
M. D. Ronsheim, C. K Zercher, J. Org. Chem., 2003, 68, 4535-4538.
The reaction of organocerium reagents, generated in situ from aryl and heteroaryl lithium compounds, with cycloalkanones proceeds cleanly to provide alkoxides. Addition of MsCl or SOCl2 with DBU gave aryl-substituted cycloalkenes in good yields. A short total synthesis of (±)-laurokamurene B is described.
J. Tallineau, G. Bashiardes, J.-M. Coustard, F. Lecornué, Synlett, 2009, 2761-2764.