Ruthenium-Catalyzed (2 + 2) Intramolecular Cycloaddition of Allenenes
作者:Moisés Gulías、Alba Collado、Beatriz Trillo、Fernando López、Enrique Oñate、Miguel A. Esteruelas、José L. Mascareñas
DOI:10.1021/ja200784n
日期:2011.5.25
We report a ruthenium-catalyzed (2 + 2) intramolecularcycloaddition of allenes and alkenes. We have found that the use of the ruthenium complex RuH(2)Cl(2)(P(i)Pr(3))(2), which has previously gone unnoticed in catalytic applications, is crucial for the observed reactivity. The reaction proceeds under mild conditions and is fully diastereoselective, providing a practical entry to a variety of bicyclo[3
[2+2] Cycloaddition of 1,3-Dienes by Visible Light Photocatalysis
作者:Anna E. Hurtley、Zhan Lu、Tehshik P. Yoon
DOI:10.1002/anie.201405359
日期:2014.8.18
[2+2] Photocycloadditions of 1,3‐dienes represent a powerful yet synthetically underutilized class of reactions. We report that visiblelight absorbing transition metal complexes enable the [2+2] cycloaddition of a diverse range of 1,3‐dienes. The ability to use long‐wavelength visiblelight is attractive because these reaction conditions tolerate the presence of sensitive functional groups that might
Stereocontrolled Synthesis of <i>Z</i>-Dienes via an Unexpected Pericyclic Cascade Rearrangement of 5-Amino-2,4-pentadienals
作者:Sarah E. Steinhardt、Joel S. Silverston、Christopher D. Vanderwal
DOI:10.1021/ja8028125
日期:2008.6.18
Donor-acceptor dienes known as Zincke aldehydes, which derive readily from the ring-opening reactions of pyridinium salts with secondary amines, undergo a fascinating thermal rearrangement reaction to afford Z-alpha,beta,gamma,delta-unsaturated amides with excellent stereoselectivity. Efficient, stereocontrolled access to Z-trisubstituted alkenes with two different substitution patterns is possible
Synthesis of labile all-trans-7,8,7′,8′-bis-acetylenic carotenoids by bi-directional Horner–Wadsworth–Emmons condensation
作者:Belén Vaz、Noelia Fontán、Marta Castiñeira、Rosana Álvarez、Ángel R. de Lera
DOI:10.1039/c4ob02144d
日期:——
Two symmetrical C7,C8-acetylenic carotenoids have been stereoselectively prepared using a bi-directional Horner–Wadsworth–Emmons condensation of the C10-dialdehyde and C15-phosphonates.
Synthetic Studies and Mechanistic Insight in Nickel-Catalyzed [4+2+1] Cycloadditions
作者:Yike Ni、John Montgomery
DOI:10.1021/ja057741q
日期:2006.3.1
with alkynes tethered to dienes has been developed. A broad range of unsaturated substrates participate in the sequence, and stereoselectivities are generally excellent. Stereochemicalstudies provided evidence for a mechanism that involves the [3,3] sigmatropicrearrangement of divinylcyclopropanes.