Photocycloaddition reactions of the first stable thioaldehyde: 2,4,6-tri(tert-butyl)thiobenzaldehyde with substituted allenes
作者:G. Hofstra、J. Kamphuis、H.J.T. Bos
DOI:10.1016/s0040-4039(01)80050-2
日期:1984.1
Irradiation of 2,4,6-tri-(tert,-butyl)thiobenzaldehyde 1 with some alkoxy-, alkylthio-, and phenyl-allenes 2 a-i gave one stereoisomer of a (2+2)-cycloadduct, viz. thietane 3 in high yields (75–95%). Ringclosure is in agreement with MNDO-calculations.
Enantiospecific synthesis of 1,3-disubstituted allenes by palladium-catalyzed coupling of propargylic compounds with arylboronic acids
作者:Masahiro Yoshida、Tatsuro Okada、Kozo Shishido
DOI:10.1016/j.tet.2007.05.035
日期:2007.7
An enantiospecific coupling of propargylic esters and carbonates with arylboronicacids has been developed using a palladium catalyst. Optically active 1,3-disubstituted allenes were synthesized with high enantiomeric excesses by carrying out the reactions under basic aqueous conditions.
Silver(<scp>i</scp>)-mediated highly enantioselective synthesis of axially chiral allenes under thermal and microwave-assisted conditions
作者:Vanessa Kar-Yan Lo、Cong-Ying Zhou、Man-Kin Wong、Chi-Ming Che
DOI:10.1039/b914516h
日期:——
Silver(I) salts mediated stereospecifictransformation of opticallyactive propargylamines to axially chiral allenes with excellent enantioselectivities (17 examples with 96-99% ee; one substrate with 91% ee) without subsequent racemization.
Rearrangements and Stereomutations of Metallacycles Derived from Allenes and Imidozirconium Complexes
作者:Forrest E. Michael、Andrew P. Duncan、Zachary K. Sweeney、Robert G. Bergman
DOI:10.1021/ja045607k
日期:2005.2.1
azametallacyclobutenes generated via [2+2] cycloaddition of allenes and imidozirconium complexes have been studied. Metallacycles derivedfromallenes bearing beta-hydrogen atoms racemize at room temperature by reversible beta-hydride elimination, a process which is also responsible for their eventual conversion to monoazadiene complexes. Metallacycles derivedfrom diarylallenes racemize by reversible thermal bond
Chiral allenes are readily accessed in a single pot operation in the reaction of terminal alkynes, aldehydes, chiral secondary amines, and zinc halides in good yields (up to 77% yield) and excellent enantioselectivities (up to 99% ee) in toluene at 120 °C. The reaction proceeds through initial formation of chiral propargylamine intermediates with creation of a new stereogenic center and subsequent