You Huang

Phosphine-Catalyzed Domino Reaction: Highly Stereoselective Synthesis of trans-2,3-Dihydrobenzofurans from Salicyl N-Thiophosphinyl Imines and Allylic Carbonates

A novel phosphine-catalyzed domino reaction of salicyl N-thiophosphinyl imines and allylic carbonates was developed. The allylic carbonate, in this reaction, serves as a new kind of 1,1-dipolar synthon. This method offered a powerful approach to the construction of a highly substituted trans-2,3-dihydrobenzofuran skeleton with high diastereoselectivity.

PPh3-catalyzed domino reaction: a facile method for the synthesis of chroman derivatives.

A novel domino reaction catalyzed by triphenylphosphine was developed for synthesis of the highly functionalized chroman derivatives. The first example that the gamma-CH(3) of allenoate undergoes cyclization to form chroman derivates was reported.

Phosphine-Catalyzed [4 + 2] Annulation of γ-Substituent Allenoates: Facile Access to Functionalized Spirocyclic Skeletons

The first phosphine-catalyzed [4 + 2] annulation of γ-substituted allenoates with 2-arylidene-1H-indene-1,3(2H)-diones is disclosed. In the reaction, the γ-substituted allenoate serves as a new type of 1,4-dipolar synthon; this broadens the application of γ-substituted allenoates. This method also offers a powerful approach to the construction of highly substituted spiro[4.5]dec-6-ene skeletons in excellent yields, and with complete regioselectivity and high diastereoselectivity.

Substrate-Controlled, Phosphine-Catalyzed Domino Reactions of Activated Conjugated Dienes: Highly Diastereoselective Synthesis of Bicyclic Skeletons

The introduction of the domino reaction as a concept in organic synthesis has inspired fruitful discoveries. A successful domino reaction depends on the selection of efficient catalysts and appropriate substrates. Our group is focused on the study of phosphine-catalyzed domino reactions based on the Morita– Baylis–Hillman (MBH) reaction and the Rauhut–Currier (RC) reaction. The phosphine-catalyzed dimerization of activated alkenes, discovered by Rauhut and Currier in 1963 and coined as Rauhut– Currier (RC) reaction by Krische, is a unique method that creates a new C C bond between the a position of an activated alkene and the b position of a second alkene. To date, considerable efforts have been directed toward the intermolecular RC reactions of simple activated alkenes and the intramolecular versions of tethered bis ACHTUNGTRENNUNG(enones).[4,7] However, domino reactions based on the RC reaction are quite limited. Two fundamental impediments have hampered the incorporation of RC reactions into domino processes. Firstly, the selectivity of cross RC coupling is poor. Moreover, the zwitterionic intermediate A can transfer to B (Scheme 1), which will readily undergo b elimination to terminate the catalytic cycle if it is not compatible with another component and hence make the further domino process impossible. In response to these two challenges, we envisioned that an activated conjugated diene might eliminate these drawbacks. The zwitterionic intermediate A’, through resonance, can exist as B’, a classical intermediate, or as B’’, a phosphorous ylide. The latter can be stabilized by an appendant enone (or enoate) and therefore has potential to trigger subsequent chemical reactions with appropriate substrates. Polycyclic dihydrofuran skeletons are widespread among various natural products of important biological activities and also serve as very useful precursors for the construction of molecular complexity such as ( )-himandrine and cyathin A3. [12] At present, however, the formation of the bicyclic dihydrofuran framework generally involves building a second fiveor six-membered ring onto a preformed dihydrofuran moiety in several steps, which dramatically weakens the overall efficiency. Cyclopentenyl phosphoranes may serve as ligands in the synthesis of many inorganic and organic complexes. To the best of our knowledge, no efficient strategy for the synthesis of bicyclic phosphoranes has been reported because the unusual stability of cyclopentenyl phosphoranes makes the traditional stepwise manipulations rather difficult. To solve these problems, we focused on the appropriate domino processes. [a] J. Ma, Dr. P. Xie, C. Hu, Prof. Dr. Y. Huang, Prof. Dr. R. Chen State Key Laboratory and Institute of Elemento-organic Chemistry Nankai University Tianjin 300071 (P.R. China) Fax: (+86) 22-23503627 E-mail : hyou@nankai.edu.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201100881. Scheme 1. General concept. RC=Rauhut–Currier.

Highly Enantioselective Intermolecular Cross Rauhut–Currier Reaction Catalyzed by a Multifunctional Lewis Base Catalyst†

The highly enantioselective intermolecular cross Rauhut-Currier reaction of different active olefins catalyzed by a multifunctional chiral Lewis base was reported. The RC products were obtained in excellent yields (up to 98 %), high chemo- and enantioselectivity (up to 96 % ee). The reaction could be performed on a gram scale using 1 mol % of the multifunctional phosphine catalyst.

Phosphine‐Mediated Domino Benzannulation Strategy for the Construction of Highly Functionalized Multiaryl Skeletons

A skeleton crew: A phosphine-mediated domino benzannulation strategy was developed for the synthesis of multiaryl skeletons (see scheme). A wide range of aromatic compounds and functional groups can be assembled into a multiaryl molecule through a core domino process.

Phosphine-catalyzed domino benzannulation: an efficient method to construct biaryl skeletons.

The first phosphine-catalyzed domino benzannulation reaction to prepare a variety of functionalized biaryls from allenoates and dienic sulfones is developed.

Domino Reaction for the Chemo- and Stereoselective Synthesis of trans-2,3-Dihydrobenzofurans from N-Thiophosphinyl Imines and Sulfur Ylides

A novel domino annulation between sulfur ylides and salicyl N-thiophosphinyl imines was developed. The method allows the synthesis of a highly substituted trans-2,3-dihydrobenzofuran skeleton with high yield and excellent chemo- and stereoselectivity.

Bifunctional-Phosphine-Catalyzed Sequential Annulations of Allenoates and Ketimines: Construction of Functionalized Poly-heterocycle Rings

A highly stereoselective sequential annulation reaction between γ-substituted allenoates and ketimines was reported. By using bifunctional N-acyl aminophosphine catalysts, poly-heterocycle rings were obtained with high stereocontrol in good to excellent yields. The desired products have four contiguous stereogenic centers (one quaternary and three tertiary carbon centers), and only one isomer was obtained in all reactions.

Phosphine-Catalyzed Rauhut–Currier Domino Reaction: A Facile Strategy for the Construction of Highly Functionalized Cyclopentene

anionic, cationic, and free-radical-mediated [3+2] cycloaddition have been investigated. In recent years, phosphine-catalyzed [3+2] cycloaddition, developed by Lu and Zhang in 1995, has inspired fruitful discoveries, especially for preparing various carbocycles and heterocycles. However, owing to the highly and versatile reactivity of allenoates, the control of chemoand regioselectivity is often problematic. Therefore, a convenient and efficient method for the construction of highly functionalized cyclopentene skeletons is in great demand. The Rauhut–Currier (RC) reaction is a unique method that creates a new C C bond between the a-position of an activated alkene and the b-position of a second alkene. Even though significant progress has been made, controlling selectivity in cross-coupling reactions involving different activated alkenes is still a challenge. Based on these pioneering studies and our studies on phosphine-catalyzed domino reactions, we have successfully constructed cyclohexene and heterocyclic compounds through intermolecular RC reaction. These studies showed that the efficiency of formation of these skeletons is highly catalystand substrate-dependent. Recently, our group found the diverse reactivity of conjugated dienes and realized a tunable intermolecular RC domino reaction leading to two distinct bicyclic skeletons, which initiated our further investigation (Scheme 1). To the best of our knowledge, Marinetti et al. reported aza-Morita–