A direct synthesis of olefins by reaction of carbonyl compounds with lithio derivatives of 2-[alkyl- or (2′-alkenyl)- or benzyl-sulfonyl]-benzothiazoles.
作者:Jean Bernard Baudin、Georges Hareau、Sylvestre A. Julia、Odile Ruel
DOI:10.1016/s0040-4039(00)92037-9
日期:1991.2
During the title reaction, the lithium alkoxides formed as intermediates undergo an intramolecular addition to the neighboring CN group followed an S to 0 benzothiazole transfer and simultaneous extrustion of sulfur dioxide and ejection of 2(3H)-benzothiazolone anion.
Synthesis of Exocyclic Trisubstituted Alkenes
<i>via</i>
Nickel‐ Catalyzed Kumada‐Type Cross‐Coupling Reaction of
<i>gem</i>
‐ Difluoroalkenes with Di‐Grignard Reagents
作者:Wenpeng Dai、Xuxue Zhang、Juan Zhang、Yingyin Lin、Song Cao
DOI:10.1002/adsc.201500889
日期:2016.1.21
A practical, nickel‐catalyzed Kumada‐type double cross‐coupling reaction of gem‐difluoroalkenes with 1,4‐ or 1,5‐di‐Grignard reagents was developed. The reaction proceeded efficiently at room temperature and a variety of cyclization products, arylmethylenecyclopentanes and arylmethylenecyclohexanes, were obtained in high to excellent yields, respectively.
Direct catalytic cross-coupling of alkenyllithium compounds
作者:Valentín Hornillos、Massimo Giannerini、Carlos Vila、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1039/c4sc03117b
日期:——
A catalytic method for the direct cross-coupling of alkenyllithium reagents with aryl and alkenylhalides is described. The use of a catalyst comprising Pd2(dba)3/XPhos allows for the stereoselective preparation of a wide variety of substituted alkenes in high yields under mild conditions. In addition (1-ethoxyvinyl)lithium can be efficiently converted into substituted vinyl ethers which, after hydrolysis
Depending on the kind of R1 and R2, cyclic carbonates 1, in the presence of 10 mol% of Pd(PPh3)4 and 10 equiv of paraformaldehyde, selectively undergo three types of reaction: 1 (R1, R2 ≠ H) give dienes 3 exclusively; 1 (R1 = R2 = H and R1 ≠ H, R2 = H) furnish 6-vinyl-1,3-dioxanes 5 exclusively, while 1 (R1 = H, R2 ≠ H) give rise to 4-pentenyl formates 4 selectively (together with 3 as the minor products)
We describe a 1,3-boron shift-type reaction of homoallenylboronates at the center (sp) carbon in allenes to afford 2-boryl-1,3-dienes with a variety of substituents.