Phosphine-Catalyzed Synthesis of 3,3-Spirocyclopenteneoxindoles from γ-Substituted Allenoates: Systematic Studies and Targeted Applications
摘要:
The phosphine-promoted [3 + 2] cyclizations between gamma-substituted allenoates and arylideneoxindoles have been applied to the stereoselective synthesis of spiro(cyclopentene)oxindoles with trisubstituted cyclopentene units. It has been demonstrated that PPh3 operates a very efficient control of the relative stereochemistry of the three stereogenic centers of the final spiranic products. Focused experiments have been carried out then so as to access carbocyclic analogues of an important series of anticancer agents inhibiting MDM2-p53 interactions.
Power of P: Phosphine‐promoted [3+2] annulation reactions between electron‐poor allenes and 3‐arylidene indolin‐2‐ones afford a new organocatalytic strategy for the synthesis of the spirocyclic core of oxindolic cyclopentanes (see scheme). Asymmetric variants of these reactions have been implemented by using chiral catalysts, giving very high levels of asymmetric induction.
A highly enantioselective [4+2] annulation with respect to allenoates and 3-olefinic oxindoles catalyzed by Lewis base was reported, which proved to be an efficient way to synthesize chiral dihydropyran-fused indoles. The cycloaddition products were generally obtained in high yields (up to 98%) with very good enantioselectivities (up to 94% enantiomeric excess).
Construction of Pyrrolidinyl Spirooxindoles via a 1,3-Dipolar Cycloaddition Reaction of (<i>E</i>)-<i>N</i>-Boc-3-Alkylidene-Indolin-2(3<i>H</i>)ones with Azomethine Ylides
作者:Zhang-Biao Yu、Xiong-Li Liu、Bo-Wen Pan、Bin Chen、Ying Zhou、Hua-Lin Wang
DOI:10.1080/00397911.2013.820834
日期:2014.2.16
A mild and efficient method for the construction of pyrrolidinyl spirooxindoles via a 1,3-dipolar cycloaddition reaction of (E)-N-Boc-3-alkylidene-indolin-2(3H)ones with azomethine ylides has been established. The presence of an N-Boc group in the indolin-2(3H)ones obviously increased the activity and stereoselectivity of the reaction, affording the desired pyrrolidinyl spirooxindoles 4 with up to 85% yield and up to >99/1 dr value. Furthermore, the antibacterial activity of these compounds against Staphylococcus aureus (ATCC-25825) has been tested at minimum concentration, and some of them exhibit moderate antibacterial activity. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) for the following free supplemental resource(s): Full experimental and spectral details.]
Synthesis of 3,3′-Spirocyclic Oxindoles via Phosphine Catalyzed [4 + 2] Cyclizations
Triphenylphosphine promoted reactions between 3-arylideneoxindoles and (delta-aryl-substituted penta-2,3-dienoates afford an unprecedented access to spirocyclic oxindoles with functionalized six-membered rings. In these new [4 + 2] cyclization processes, the allenoates operate as the four-carbon synthons, thanks to the involvement of the substituted (delta-carbons. These reactions give excellent control of the relative stereochemistry of the three stereogenic centers. The stereochemistry of the final product has been ascertained by X-ray diffraction studies.
Phosphine-Catalyzed Synthesis of 3,3-Spirocyclopenteneoxindoles from γ-Substituted Allenoates: Systematic Studies and Targeted Applications
The phosphine-promoted [3 + 2] cyclizations between gamma-substituted allenoates and arylideneoxindoles have been applied to the stereoselective synthesis of spiro(cyclopentene)oxindoles with trisubstituted cyclopentene units. It has been demonstrated that PPh3 operates a very efficient control of the relative stereochemistry of the three stereogenic centers of the final spiranic products. Focused experiments have been carried out then so as to access carbocyclic analogues of an important series of anticancer agents inhibiting MDM2-p53 interactions.