Pd-catalyzed 5-endo-trig-type cyclization of β,γ-unsaturated carbonyl compounds: an efficient ring closing reaction to give γ-butenolides and 3-pyrrolin-2-ones
作者:Gan B. Bajracharya、Priti S. Koranne、Rashid N. Nadaf、Randa Kassem Mohamed Gabr、Kazuhiro Takenaka、Shinobu Takizawa、Hiroaki Sasai
DOI:10.1039/c0cc02352c
日期:——
The 5-endo-trig-type cyclization has been performed using a Pd-bis(isoxazoline) catalyst. The present cyclization of beta,gamma-unsaturated carbonylcompounds gave gamma-butenolides and 3-pyrrolin-2-ones in good to excellent yields.
Abstract The combination of dimethylsulfoxide and oxalyl bromide was used to accomplish the cyclization of 3-alkenoic acids with the aid of a base to afford γ-butenolides, in which bromodimethylsulfonium salt generated in situ was proposed to serve as a Br+ source. GRAPHICAL ABSTRACT
Kinetic Resolution of Racemic Lactones by Conjugate Additions of Allylic Organolithium Species: Direct Formation of Three Contiguous Centers with High Diastereo- and Enantioselectivities
作者:Sung H. Lim、Peter Beak
DOI:10.1021/ol0263898
日期:2002.8.1
[reaction: see text] Kinetic resolution of racemic alpha,beta-unsaturated lactones by the organolithium species produced from asymmetric lithiation of N-Boc-N-(p-methoxyphenyl)cinnamylamine provides conjugateaddition products with three contiguous stereogenic centers in yields of 62-77% with diastereomeric ratios from 75:25 to >99:1 and enantiomeric ratios for the major diastereomers from 94:6 to 98:2
Regioselective alkylation of 2-trimethylsiloxyfuran; direct access to 4-substituted but-2-en-4-olides
作者:Charles W. Jefford、Adam W. Sledeski、John Boukouvalas
DOI:10.1039/c39880000364
日期:——
Primary iodides alkylate 2-trimethylsiloxyfuran in the presence of a molar excess of silver trifluoroacetate to give the 4-alkylbut-2-en-4-olides in 55–81% yield; as an illustration of the method, the cytotoxic marine sponge constituent, 4-(methoxycarbonylmethyl)but-2-en-4-olide was prepared in 79% yield in one step.