Asymmetric α-amination of 3-substituted oxindoles using chiral bifunctional phosphine catalysts

• Qiao-Wen Jin,
• Zhuo Chai,
• You-Ming Huang,
• Gang Zou and
• Gang Zhao

Beilstein J. Org. Chem. 2016, 12, 725–731, doi:10.3762/bjoc.12.72

• a variety of reactions such as aza-Morita–Baylis–Hillman reactions [19][20][21], Rauhut–Currier reactions [22][23][24][25][26][27], Michael addition reactions [28][29][30][31][32][33][34][35], and various cycloadditions [36][37][38][39]. In recent years, our group has focused on the development of

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

• Laura A. Bryant,
• Rossana Fanelli and
• Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

• their derivatives in asymmetric organocatalysis over the last five years or so [13][14]. The review is organized by reaction type, beginning with the Morita–Baylis–Hillman process – one of the first reactions to utilize 6’-OH-cinchona alkaloid derivatives in asymmetric organocatalysis. The focus will

• cinchona class of alkaloids are a dynamic and versatile type of organocatalyst that should be included in the screening libraries of chemists seeking to develop asymmetric methodologies. Review Morita–Baylis–Hillman (MBH) and MBH-carbonate reactions The first reports of an asymmetric reaction catalyzed by

• a cinchona organocatalyst with a 6’-OH functionality came from Hatakeyama and co-workers in 1999 who demonstrated the use of β-ICPD in an asymmetric Morita–Baylis–Hillman (MBH) reaction [15][16][17][18] what is essentially an asymmetric C3-substituted ammonium enolate reaction (Scheme 1) [19][20

Application of 7-azaisatins in enantioselective Morita–Baylis–Hillman reaction

• Qing He,
• Gu Zhan,
• Wei Du and
• Ying-Chun Chen

Beilstein J. Org. Chem. 2016, 12, 309–313, doi:10.3762/bjoc.12.33

• in diverse biologically active substances. Here 7-azaisatins turned out to be more efficient electrophiles than the analogous isatins in the enantioselective Morita–Baylis–Hillman (MBH) reactions with maleimides using a bifunctional tertiary amine, β-isocupreidine (β-ICD), as the catalyst. This route

• reaction; Introduction The asymmetric Morita–Baylis–Hillman (MBH) reaction is one of the most powerful synthetic methods in organic chemistry, as it directly constructs carbon–carbon bonds in an atom-economical manner and provides densely functionalized molecules [1][2][3][4]. In particular, the direct

• high yield by using N-methylisatin (4) as the substrate (Scheme 1). Conclusion In summary, we have developed an efficient and enantioselective Morita–Baylis–Hillman reaction between 7-azaisatins and maleimides and other activated alkenes in the presence of the bifunctional catalyst β-ICD. 7-Azaisatins

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• –Baylis–Hillman-type reaction [62]. Anodic methoxylation can be combined with biocatalytic approaches to prepare stereodivergent 4-hydroxypiperidines [63]. 3-Hydroxy-6-substituted piperidines inaccessible by conventional synthesis approaches can also be effectively synthesised by anodic methoxylation [64

• sulfinates afforded stable crystalline precursors of N-acyliminium ions that are activated by base [60]. The anodic methoxylation products of unfunctionalised amides can be converted to carbonyl compounds (aldehydes or esters) by treatment with cobaltacene [61] or be used as starting materials for the Morita

Morita–Baylis–Hillman reaction of acrylamide with isatin derivatives

• Radhey M. Singh,
• Kishor Chandra Bharadwaj and
• Dharmendra Kumar Tiwari

Beilstein J. Org. Chem. 2014, 10, 2975–2980, doi:10.3762/bjoc.10.315

• Abstract The Morita–Baylis–Hillman reaction of acrylamide, as an activated alkene, has seen little development due to its low reactivity. We have developed the reaction using isatin derivatives with acrylamide, DABCO as a promoter and phenol as an additive in acetonitrile. The corresponding aza version

• with acrylate and acrylonitrile has also been developed resulting in high product yields. Keywords: acrylamide; isatin; ketimine; Morita–Baylis–Hillman; phenol; Introduction The Morita–Baylis–Hillman (MBH) reaction is an important carbon–carbon bond-forming reaction [1][2][3]. It involves the

• and in 91% yield in just 3 hours of reaction (Table 2, entry 1) was achieved. Encouraged by these results, the focus was shifted to the development of this aza-Morita–Baylis–Hillman reaction using isatin-derived ketimines [51][52][53]. This reaction could also lead to the construction of tertiary

Total synthesis of the proposed structure of astakolactin

• Takayuki Tonoi,
• Keisuke Mameda,
• Moe Fujishiro,
• Yutaka Yoshinaga and
• Isamu Shiina

Beilstein J. Org. Chem. 2014, 10, 2421–2427, doi:10.3762/bjoc.10.252

• . The construction of the α-methylene-β-hydroxy ester moiety in 5, which is commonly known as a Morita–Baylis–Hillman adduct, would be achieved via an aldol reaction between aldehyde 6 and ester 7, followed by oxidative deselenization [37]. The linear precursor 8 would be prepared from (E,E)-farnesol

• provided aldehyde 6. The aldol reaction of 6 with ester 7 in the presence of base and the subsequent oxidative deselenization of the resulting adduct 14 yielded a Morita–Baylis–Hillman-type product 5 [37] in two steps. Reduction of 5 and the regioselective protection of the less-hindered primary hydroxy

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita–Baylis–Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and

• developments in nucleophilic chiral phosphine-catalyzed asymmetric reactions, including annulations of allenes, ketenes, alkynes, and Morita–Baylis–Hillman (MBH) carbonates with activated alkenes and imines, allylic substitution of MBH acetates and carbonates, Michael additions, γ-umpolung additions, and

Regioselective S_N2' Mitsunobu reaction of Morita–Baylis–Hillman alcohols: A facile and stereoselective synthesis of α-alkylidene-β-hydrazino acid derivatives

• Silong Xu,
• Jian Shang,
• Junjie Zhang and
• Yuhai Tang

Beilstein J. Org. Chem. 2014, 10, 990–995, doi:10.3762/bjoc.10.98

• Silong Xu Jian Shang Junjie Zhang Yuhai Tang Department of Chemistry, School of Science, Xi’an Jiaotong University, Xi’an 710049, P. R. China 10.3762/bjoc.10.98 Abstract A highly regioselective SN2' Mitsunobu reaction between Morita–Baylis–Hillman (MBH) alcohols, azodicarboxylates, and

• under mild conditions is still desirable. Morita–Baylis–Hillman (MBH) adducts [9] are a class of unique substrates of great synthetic potential which contain three manipulatable groups, namely, a hydroxy group, a carbon–carbon double bond, and an electron-withdrawing group. Over the past several decades

• SN2' Mitsunobu reaction between Morita–Baylis–Hillman (MBH) alcohols, azodicarboxylates, and triphenylphosphine as an efficient synthetic method for α-alkylidene-β-hydrazino acid derivatives in high yields and good stereoselectivity. This reaction features additional advantages as mild conditions

Regioselective 1,4-trifluoromethylation of α,β-unsaturated ketones via a S-(trifluoromethyl)diphenylsulfonium salts/copper system

• Satoshi Okusu,
• Yutaka Sugita,
• Etsuko Tokunaga and
• Norio Shibata

Beilstein J. Org. Chem. 2013, 9, 2189–2193, doi:10.3762/bjoc.9.257

• of 1,4-additive trifluoromethylation of (trifluoromethyl)trimethylsilane (Me3SiCF3, Ruppert–Prakash reagent) to very specific substrates such as trans-1-benzoyl-2-(dimethylamino)ethylene [12], 2-polyfluoroalkylchromones [13][14], isoxazoles with a nitro group at the 4-position [15], and Morita–Baylis

• –Hillman adducts (via SN2’ [16] or successive SN2’/SN2’ mode [17]). Sevenard and co-workers reported the nucleophilic 1,4-trifluoromethylation to chromones, coumarins and cyclohex-2-enone using the Ruppert–Prakash reagent, which was achieved by blocking the carbonyl moiety of the substrates with a bulky

Asymmetric allylic alkylation of Morita–Baylis–Hillman carbonates with α-fluoro-β-keto esters

• Lin Yan,
• Zhiqiang Han,
• Bo Zhu,
• Caiyun Yang,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2013, 9, 1853–1857, doi:10.3762/bjoc.9.216

• and Biological Chemistry, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 10.3762/bjoc.9.216 Abstract In the presence of a commercially available Cinchona alkaloid as catalyst, the asymmetric allylic alkylation of Morita–Baylis–Hillman carbonates, with α-fluoro-β-keto esters as

• ). Keywords: allylic alkylation; asymmetric catalysis; fluorine; fluoro-β-keto esters; Morita–Baylis–Hillman carbonates; natural product; Introduction Fluorine is the most electronegative element in the periodic table, resulting in a highly polar C–F bond. This gives fluoro-organic compounds unique

• introduction of fluorine atoms in molecules has become one of the most exciting and intense research areas in the recent years. Lewis base-catalyzed asymmetric allylic alkylations (AAA) of Morita–Baylis–Hillman (MBH) adducts [5][6], such as acetates and carbonates, have become an attractive option to access

Preparation of optically active bicyclodihydrosiloles by a radical cascade reaction

• Koichiro Miyazaki,
• Yu Yamane,
• Ryuichiro Yo,
• Hidemitsu Uno and
• Akio Kamimura

Beilstein J. Org. Chem. 2013, 9, 1326–1332, doi:10.3762/bjoc.9.149

• triethylgermyl radical to enyne 1a was slow and less efficient. Conclusion In conclusion, we have successfully converted chiral enyne compounds 1, which were readily available from an asymmetric aza-Morita–Baylis–Hillman equivalent reaction, into bicyclic pyrolidinodihydrosiloles 2 in good yields. These

Titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes: An efficient route for the synthesis of stereodefined allylic amines

• Kebin Mao,
• Guoqin Fan,
• Yuanhong Liu,
• Shi Li,
• Xu You and
• Dan Liu

Beilstein J. Org. Chem. 2013, 9, 621–627, doi:10.3762/bjoc.9.69

• ], iodocyclocarbamates [19] and isoxazolines [20]. Although it has been reported that allylic amines can be synthesized by methods such as amination of allylic alcohols [21][22][23][24], direct allylic amination of simple alkenes [25][26][27], Morita–Baylis–Hillman reaction [28], alkenylation of imines [29][30][31][32

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• catalyst activates and orients the β-ketoester. Morita–Baylis–Hillman (MBH) reaction The Morita–Baylis–Hillman (MBH) reaction provides a very useful and interesting method for the synthesis of β-hydroxycarbonyl compounds with an α-alkylidene group [49][50][51][52][53]. Mechanochemical methods of neat

Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach

• Florian Boeck,
• Max Blazejak,
• Markus R. Anneser and
• Lukas Hintermann

Beilstein J. Org. Chem. 2012, 8, 1630–1636, doi:10.3762/bjoc.8.186

• established catalysts in Morita–Baylis–Hillman type reactions, where they add to conjugated acceptor systems [39]. Tests with either nitrogen bases (Table 1, entries 2–5) or N-heterocyclic carbenes (Table 1, entry 6) were not rewarded with success. Finally, phosphanes were tested, and while triphenylphosphane

Reactions of nitroxides XIII: Synthesis of the Morita–Baylis–Hillman adducts bearing a nitroxyl moiety using 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl as a starting compound, and DABCO and quinuclidine as catalysts

• Jerzy Zakrzewski

Beilstein J. Org. Chem. 2012, 8, 1515–1522, doi:10.3762/bjoc.8.171

• Jerzy Zakrzewski Institute of Industrial Organic Chemistry, Annopol 6, 03-236 Warsaw, Poland 10.3762/bjoc.8.171 Abstract The Morita–Baylis–Hillman adducts bearing a nitroxyl moiety were synthesized from 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl and aliphatic, aryl and heterocyclic

• aldehydes. Keywords: 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl; DABCO; Morita–Baylis–Hillman reaction; nitroxides; quinuclidine; Introduction In the Morita–Baylis–Hillman (MBH) reaction, aldehydes react with a double bond activated by an electron-withdrawing group (EWG). The vinylic carbon

Cation affinity numbers of Lewis bases

• Christoph Lindner,
• Raman Tandon,
• Boris Maryasin,
• Evgeny Larionov and
• Hendrik Zipse

Beilstein J. Org. Chem. 2012, 8, 1406–1442, doi:10.3762/bjoc.8.163

• acceptors (addition). Taking the (aza-)Morita–Baylis–Hillman reaction as an example the first step of the catalytic cycle involves the attack of N- or P-centered nucleophiles to a Michael acceptor (equation 10, Scheme 10). In contrast to the Lewis base additions to cationic electrophiles discussed above, in

Organocatalytic asymmetric allylic amination of Morita–Baylis–Hillman carbonates of isatins

• Hang Zhang,
• Shan-Jun Zhang,
• Qing-Qing Zhou,
• Lin Dong and
• Ying-Chun Chen

Beilstein J. Org. Chem. 2012, 8, 1241–1245, doi:10.3762/bjoc.8.139

• investigation of a Lewis base catalyzed asymmetric allylic amination of Morita–Baylis–Hillman carbonates derived from isatins afforded an electrophilic pathway to access multifunctional oxindoles bearing a C3-quaternary stereocenter, provided with good to excellent enantioselectivity (up to 94% ee) and in high

• yields (up to 97%). Keywords: allylic amination; asymmetric organocatalysis; Morita–Baylis–Hillman carbonates; 2-oxindoles; quaternary chiral center; Introduction Chiral 3-amino-2-oxindoles are versatile and useful units for the preparation of natural products and drug candidates, such as the

• the other hand, the asymmetric addition to electrophilic imines of isatins is also an attractive pathway, and a variety of examples have been presented [16][17][18][19][20][21]. Recently, we have developed the asymmetric allylic alkylation reactions [22] with Morita–Baylis–Hillman (MBH) carbonates of

Chiral multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita–Baylis–Hillman carbonates with maleimides

• Hong-Ping Deng,
• De Wang,
• Yin Wei and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 1098–1104, doi:10.3762/bjoc.8.121

• of Chemistry & Molecular Engineering, East China University of Science and Technology, and 130 MeiLong Road, Shanghai 200237, People’s Republic of China 10.3762/bjoc.8.121 Abstract We have developed a multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita–Baylis–Hillman

• previous literature. Keywords: asymmetric [3 + 2] annulation; maleimides; Morita–Baylis–Hillman carbonates; multifunctional thiourea-phosphine; organocatalysis; Introduction Highly functionalized cyclopentene derivatives are important subunits in a variety of biologically active molecules and have

Synthesis of axially chiral oxazoline–carbene ligands with an N-naphthyl framework and a study of their coordination with AuCl·SMe₂

• Feijun Wang,
• Shengke Li,
• Mingliang Qu,
• Mei-Xin Zhao,
• Lian-Jun Liu and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 726–731, doi:10.3762/bjoc.8.81

• type of axially chiral ligand 7 with an N-naphthyl framework (Figure 2) instead of traditional binaphthyl framework [15]. Their palladium complexes 8 showed high stereoselectivities in asymmetric allylic arylations to achieve the kinetic resolution of Morita–Baylis–Hillman adducts, affording up to 99

• % ee of the (E)-allylation products and 92% ee of the recovered Morita–Baylis–Hillman adducts. These intriguing results stimulated us to further develop the axially chiral oxazoline–carbene ligands 7 with an N-naphthyl framework and to evaluate their coordination with AuCl·SMe2. Results and Discussion

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• the terminal position of the double bond due to steric effects. On the basis of the above mentioned results, a proposed mechanism for the formation of 5a–h is outlined in Scheme 1. Trialkylphosphine catalysed Morita-Baylis-Hillman reaction is well studied by a number of groups [37][38][39]. Addition