Allenes and acetylenes. 22. Mechanistic aspects of the allene-forming reductions (SN2' reaction) of chiral propargylic derivatives with hydride reagents
Copper Hydride Catalyzed Enantioselective Synthesis of Axially Chiral 1,3-Disubstituted Allenes
作者:Liela Bayeh-Romero、Stephen L. Buchwald
DOI:10.1021/jacs.9b07582
日期:2019.9.4
The general enantioselective synthesis of axially chiral disubstituted allenes from prochiral starting materials remains a long-standing challenge in organic synthesis. Here, we report an efficient enantio- and chemoselective copper hydride catalyzed semireduction of conjugated enynes to furnish 1,3-disubstituted allenes using water as the proton source. This protocol is sufficiently mild to accommodate
Enantioselective and regioselective nickel-catalyzed multicomponent coupling of chiral allenes, aromatic aldehydes, and silanes
作者:Sze-Sze Ng、Timothy F. Jamison
DOI:10.1016/j.tet.2005.08.063
日期:2005.11
developed, nickel-catalyzed multicomponent coupling of chiral allenes, aromatic aldehydes, and silanes is described. The axial chirality of the allene is transferred completely to the product, a trisubstituted Z-allylic alcohol protected as a silyl ether. A very high preference for sp rather than sp2 coupling is observed, and differentially substituted allenes undergo highly site-selective coupling. These
Concise allene synthesis from propargylic alcohols by hydrostannation and deoxystannylation: A new route to chiral allenes
作者:Toshiro Konoike、Yoshitaka Araki
DOI:10.1016/s0040-4039(00)61198-x
日期:1992.8
Propargylicalcohols were converted to allenes in a two-step one-pot process comprised of hydrostannation of propargylicalcohols and subsequent deoxystannylation. Chiral (S)-2,3-decadiene of high enantiomeric excess (ee) can be prepared in a similar way.
Mecanismes de la protonolyse des organo-chromiques issus de bromures propargyliques.
作者:Bernard Cazes、Catherine Verniere、Jacques Gore
DOI:10.1016/s0040-4039(00)87652-2
日期:1982.1
The reaction of CrCl2 with propargylic bromides leads to an allenic organo—chromic derivative protonated without rearrangement by carboxylic acids. Alcohols like methol transform this metallic to its propargylic isomer and then protonate it with rearrngement (SEi′ type mechanism).