Chiral Macrocycle-Catalyzed Highly Enantioselective Phenylacetylene Addition to Aliphatic and Vinyl Aldehydes
作者:Zi-Bo Li、Tian-Dong Liu、Lin Pu
DOI:10.1021/jo070091j
日期:2007.6.1
The 1,1‘-binaphthyl macrocycle (S)-2 is found to be an excellent catalyst for the alkyne addition to aldehydes. In the presence of (S)-2 (20 mol %) and Me2Zn (2 equiv) in THF at room temperature, the addition of phenylacetylene to linear or branched aliphatic aldehydes and vinylaldehydes gave various propargylic alcohols with 89−96% ee.
The trimethylgallium reagent was found to promote the addition of phenylacetylene to various aromatic and aliphatic aldehydes. This reaction was efficiently carried out in anhydrous CH2Cl2 at room temperature under mild conditions and the corresponding propargylic alcohols were obtained in good to excellent yields up to 98%.
New Regiospecific Catalytic Approaches to 4,5-Dihydroisoxazoles and 2,5-Dihydroisoxazoles from O-Propargylic Hydroxylamines
作者:David Knight、Anthony Proctor、John Clough
DOI:10.1055/s-0029-1219365
日期:2010.3
Unprotected O-propargylic hydroxylamines undergo generally essentially quantitative cyclisations when exposed briefly to silver nitrate adsorbed onto silica gel to give 4,5-dihydroisoxazoles [2-isoxazolines], while N-protected derivatives give the corresponding 2,5-dihydroisoxazoles [3-isoxazolines] in similarly excellent yields, given that an appropriate functionality on nitrogen is used.
On the Distribution of Linear versus Angular Naphthalenes in Aromatic Tetradehydro-Diels-Alder Reactions - Effect of Linker Structure and Steric Bulk
作者:Bhavani Shankar Chinta、Beeraiah Baire
DOI:10.1002/ejoc.201700588
日期:2017.6.23
We report here a systematic study on the aromatic tetradehydro Diels-Alder (Ar-TDDA) reaction to understand the factors which may play key role on the distribution of linear and angular naphthalene products. Two factors such as nature of structure of the linker and steric bulk of the substituent on the enyne part have been studied. It is found that the structure of the linker has tremendous role on
Access to Highly Functionalized Cyclopentenones via Diastereoselective Pauson–Khand Reaction of Siloxy-Tethered 1,7-Enynes
作者:Austin G. Gallagher、Huan Tian、Osmar A. Torres-Herrera、Shuai Yin、Anxin Xie、Daniel M. Lange、Jerica K. Wilson、Louis G. Mueller、Michael R. Gau、Patrick J. Carroll、Dionicio Martinez-Solorio
DOI:10.1021/acs.orglett.9b03255
日期:2019.11.1
Pauson–Khand reaction (PKR) of siloxy-tethered 1,7-enynes for the synthesis of cyclopentaoxasilinones has been developed. This transformation can be performed on a multigram scale and is characterized by a broad substrate scope, functional group compatibility, and high chemo- and diastereoselectivity. Oxidation of the resulting cyclopentaoxasilinones delivers stereoenriched β-alkylated cyclopentenones, which