Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• functional groups such as esters or amines (Table 13). This approach was also used for the synthesis of phosphinoxazolines [223]. Hydrophosphination of alkynes The addition of P–H to a triple bond is a highly desirable method when taking atom economy principles into account. Activated [224][225] or

Nonanebis(peroxoic acid): a stable peracid for oxidative bromination of aminoanthracene-9,10-dione

• Vilas Venunath Patil and
• Ganapati Subray Shankarling

Beilstein J. Org. Chem. 2014, 10, 921–928, doi:10.3762/bjoc.10.90

• % of the desired dibromo product in 6 h, along with the starting amine and some byproducts. The long reaction time, drastic reaction conditions, isomer formation and their separation (which is a very tedious and difficult task), and reduced bromine atom economy make these approaches economically

• unattractive. Again, in all the above processes, molecular bromine is used as the bromine source which reduces the bromine atom economy by 50% [24], as the HBr generated in the reaction is not used for further bromination and also causes pollution of the environment. This problem can be resolved by employing

Copper–phenanthroline catalysts for regioselective synthesis of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and of pyrrolo[1,2-a]phenanthrolines under mild conditions

• Rupankar Paira,
• Tarique Anwar,
• Maitreyee Banerjee,
• Yogesh P. Bharitkar,
• Shyamal Mondal,
• Sandip Kundu,
• Abhijit Hazra,
• Prakas R. Maulik and
• Nirup B. Mondal

Beilstein J. Org. Chem. 2014, 10, 692–700, doi:10.3762/bjoc.10.62

• ]quinolinium/phenanthrolinium dipole precursors and maleimide/acetylenecarboxylate dipolarophiles. High atom-economy, good to very good isolated yield of the products, short reaction time and ease of separation coupled with general applicability are the key features of this methodology. Experimental General

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• reaction efficiency and atom economy. Besides lead finding in pharmaceutical and medicinal chemistry [8][9][10] MCRs have also been recognized as a DOS tool for approaching functional π-systems [11] such as luminescent chromophores [6]. Interestingly, multicomponent syntheses of symmetrically substituted

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• ). Multicomponent reactions are convergent one-pot transformations involving three or more substrates that give a single product with high atom-economy. The reagents herein react in a sequential manner and all intermediate-steps are in equilibrium except often the last irreversible step, which provides the product

Concise, stereodivergent and highly stereoselective synthesis of cis- and trans-2-substituted 3-hydroxypiperidines – development of a phosphite-driven cyclodehydration

• Peter H. Huy,
• Julia C. Westphal and
• Ari M. P. Koskinen

Beilstein J. Org. Chem. 2014, 10, 369–383, doi:10.3762/bjoc.10.35

• to provide sufficient substance amounts for clinical tests [41][42]. Additionally, alternatives in reactions driven by the formation of phosphine oxides from phosphines (e.g. the Appel and Mitsunobu reaction) are highly desired to improve atom economy (reduced waste amounts) and to circumvent

• phosphites (P(OR)3), activated through oxidants such as iodine, have been reported to give the corresponding phosphates in a Michaelis–Arbuzow type reaction [83][84][85] (Scheme 5). In order to improve atom economy and side product separation, we rationalized that in the phosphonium intermediate III

• , respectively (entries 8–9). Whereas OP(OiPr)3 was hydrolyzed in the work up, OP(OPh)3 was not saponified and therefore still remained in the isolated product 13f. However, considering the atom economy these phosphites do not represent an alternative to P(OEt)3. Even the diols rac-12g and 12h with a sterically

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• with high levels of atom economy. Boron compounds have long been ignored in this attractive area of research despite their wide range of reactivity [10][11]. In 1993, however, Petasis and co-workers reported a new synthesis of allylamines via stepwise condensation of a secondary amine, paraformaldehyde

Flow microreactor synthesis in organo-fluorine chemistry

• Hideki Amii,
• Aiichiro Nagaki and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2013, 9, 2793–2802, doi:10.3762/bjoc.9.314

• microreactor technology to overcome long-standing problems in synthetic organofluorine chemistry are showcased. Reactions using hazardous fluorinating reagents Direct fluorination employing elemental fluorine (F2) is one of the most straightforward methods to make fluorine-containing molecules with high atom

• economy. However, handling F2 needs special care and there are a lot of practical difficulties associated with direct fluorination. Elemental fluorine is a poisonous pale yellow gas at room temperature (bp −188 °C). Reactions of organic substances with elemental fluorine are typically strongly exothermic

Bis(benzylamine) monomers: One-pot preparation and application in dendrimer scaffolds for removing pyrene from aqueous environments

• Olivia N. Monaco,
• Sarah C. Tomas,
• Meghan K. Kirrane and
• Amy M. Balija

Beilstein J. Org. Chem. 2013, 9, 2320–2327, doi:10.3762/bjoc.9.266

• principles of atom economy [15]. This simple one-step approach is in contrast to the synthesis of the oxygen analogue of 4a, the well-known AB2 bis(benzyl) ether monomer, which is prepared in three steps from 3,5-dihydroxybenzoic acid and benzyl bromide. When synthesizing the bis(benzyl) ether monomer, the

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• reaction. Both mono- and bicyclic cyclopropylanilines were viable substrates to provide the annulation products in good to excellent yields. The former gave little to poor diastereoselectivity whereas the later produced modest diastereoselectivity. The reaction has 100% atom economy. It is also overall

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• stereo-controlling of the ring-opening of epoxides is quite challenging, and the background reaction should be suppressed to achieve high enantioselectivities. However, the catalytic asymmetric ring-opening of meso-epoxides gained much attention by its unique advantages of good atom-economy and versatile

Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η¹-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results

• Rajendra K. Jangid,
• Nidhi Sogani,
• Neelima Gupta,
• Raj K. Bansal,
• Moritz von Hopffgarten and
• Gernot Frenking

Beilstein J. Org. Chem. 2013, 9, 392–400, doi:10.3762/bjoc.9.40

• in asymmetric synthesis, which is one of the most attractive methods from the atom-economy point of view [1] for producing single enantiomers selectively. Over the past three decades, a variety of reactions allowing the formation of C–H, C–C, C–N, C–O and other bonds enantioselectively have been

N-Heterocyclic carbene–palladium catalysts for the direct arylation of pyrrole derivatives with aryl chlorides

• Ismail Özdemir,
• Nevin Gürbüz,
• Nazan Kaloğlu,
• Öznur Doğan,
• Murat Kaloğlu,
• Christian Bruneau and
• Henri Doucet

Beilstein J. Org. Chem. 2013, 9, 303–312, doi:10.3762/bjoc.9.35

• with heteroarenes. Keywords: aryl chlorides; atom-economy; C–H bond activation; C–H functionalization; carbenes; palladium; pyrroles; Introduction N-Heterocyclic carbenes (NHC) have emerged as an important class of ligands in the development of homogeneous catalysis [1][2][3][4][5][6][7][8][9]. Such

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• -containing tethers. Preparatively the bisallenes are especially useful in isomerization and cycloaddition reactions of all kinds leading to the respective target molecules with high atom economy and often in high yield. Bisallenes are hence substrates for generating molecular complexity in a small number of

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• ]. Planar chiral 1,2-disubstituted ferrocene derivatives are usually synthesized by using diastereoselective ortho-lithiation of monosubstituted ferrocenes with an appropriate chiral ortho-directing substituent such as chiral amines, sulfoxides, and oxazolines [3]. However, this method suffers from low atom

• economy, and requires stoichiometric amounts of metal reagents. Functionalization of ferrocene derivatives by transition-metal-catalyzed enantioselective C–H activation is a potentially more atom-economical alternative. However, only a few catalytic C–H activation reactions of ferrocenes have been

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• 10.3762/bjoc.8.198 Abstract This review highlights the development of palladium-catalyzed C–H and N–H functionalization reactions involving indole derivatives. These procedures require unactivated starting materials and are respectful of the basic principle of sustainable chemistry tied to atom economy

Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium

• Michael Dobmeier,
• Josef M. Herrmann,
• Dieter Lenoir and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 330–336, doi:10.3762/bjoc.8.36

• activation by adjacent benzylic or carbonyl groups the reaction stops at the corresponding alkyl iodide. A quantitative mass-efficiency analysis [39] of the reaction in comparison to tosylation/LAH, Ti(III)-mediated and Barton–McCombie reduction revealed a better atom economy and mass efficiency

Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating

• Kamal Usef Sadek,
• Ramadan Ahmed Mekheimer,
• Tahany Mahmoud Mohamed,
• Moustafa Sherief Moustafa and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2012, 8, 18–24, doi:10.3762/bjoc.8.3

• a wide range of biological activities [3][4]. Multicomponent reactions (MCR) occupy an interesting position in organic synthesis because of their atom economy, simple procedures and convergent character [5][6][7]. An unresolved issue in multicomponent reactions is whether their selectivity is chemo

PEG-embedded KBr₃: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

• Sanny Verma,
• Suman L. Jain and
• Bir Sain

Beilstein J. Org. Chem. 2011, 7, 1334–1341, doi:10.3762/bjoc.7.157

• achieve highly efficient, atom economic and energy-saving organic syntheses. These multicomponent reactions (MCRs) offer many advantages over conventional multistep syntheses, such as lower costs, shorter reaction times, high atom economy, avoidance of expensive purification processes [6][7], and the fact

Synthesis of diverse dihydropyrimidine-related scaffolds by fluorous benzaldehyde-based Biginelli reaction and post-condensation modifications

• Bruno Piqani and
• Wei Zhang

Beilstein J. Org. Chem. 2011, 7, 1294–1298, doi:10.3762/bjoc.7.150

• achieved by conducting a multicomponent reaction for improved atom economy, under microwave heating for fast reaction, and with fluorous solid-phase extractions (F-SPE) for ease of purification. Keywords: Biginelli reaction; dihydropyrimidine; diversity-oriented synthesis; fluorous; Suzuki coupling

Reductive amination with zinc powder in aqueous media

• Giovanni B. Giovenzana,
• Daniela Imperio,
• Andrea Penoni and
• Giovanni Palmisano

Beilstein J. Org. Chem. 2011, 7, 1095–1099, doi:10.3762/bjoc.7.125

• look from the viewpoint of green chemistry reveals that few of the above cited alternatives meet the requirements for sustainable processes [21][22]. Modified borohydride reagents are efficient and their activity spans a large array of substrates, but their atom economy is far from optimal; NaBH(OAc)3

• first choice for NaBH(OAc)3 followed by the highly flammable tetrahydrofuran. Catalytic hydrogenation is an interesting alternative to modified borohydrides in terms of atom economy, but its application is unfortunately not general as many chemical groups must be avoided (e.g., double and triple bonds

• promoting its use as a green reductant: i) atom economy, ii) low toxicity, iii) relative stability in air and water, and iv) low cost. Examples of the reduction of imines by zinc metal are reported, either in organic solvents [25][26][27][28][29] or in basic aqueous medium [30]. We recognized that this

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• skeletons 18 could be obtained in a highly diastereoselective fashion, in good yields and in excellent atom-economy [53][54]. The above reactions involve an initial attack of a heteroatom on gold-activated alkynes. However, it is also possible to induce alternative cycloaddition reactions of alkynes that

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

• Alexandre Pradal,
• Chung-Meng Chao,
• Patrick Y. Toullec and
• Véronique Michelet

Beilstein J. Org. Chem. 2011, 7, 1021–1029, doi:10.3762/bjoc.7.116

• sustainable development and atom economy concepts [1][2][3][4][5][6][7][8]. In the last ten years, they have provided extremely efficient access to cyclic skeletons with a broad range of functional moieties. Among them, the synthesis of oxa- and azabicyclo[4.1.0]heptenes starting from heteroatom-linked 1,6

Metathesis access to monocyclic iminocyclitol-based therapeutic agents

• Ileana Dragutan,
• Valerian Dragutan,
• Carmen Mitan,
• Hermanus C.M. Vosloo,
• Lionel Delaude and
• Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

• atom economy. However, before carrying out the RCM reaction, the basic amino group (incompatible with most metathesis catalysts because of chelation to the metal center) [48] must either be protected (as N–Boc, N–Cbz, etc.), masked by incorporation into a cleavable heteroatom-containing cycle

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• to perform the EYCM with stoichiometric amounts of olefin and alkyne. This represents an economical and technical advantage compared to the classical strategy using an excess of olefin [87]. Conclusion The EYCM is a very efficient transformation which creates conjugated diene structures with atom

• economy. It has not been developed as rapidly as the olefin cross-metathesis because it suffers from some reactivity and selectivity issues that have not yet been solved. Regioselectivity of the cross-coupling reaction is usually good as no problem is encountered starting from symmetrical alkynes; and in