A new method for the synthesis of α-aminoalkylidenebisphosphonates and their asymmetric phosphonyl-phosphinyl and phosphonyl-phosphinoyl analogues

• Anna Kuźnik,
• Roman Mazurkiewicz,
• Mirosława Grymel,
• Katarzyna Zielińska,
• Jakub Adamek,
• Ewa Chmielewska,
• Marta Bochno and
• Sonia Kubica

Beilstein J. Org. Chem. 2015, 11, 1418–1424, doi:10.3762/bjoc.11.153

• -phosphinylation or α-phosphinoylation of 1-(N-acylamino)alkylphosphonates, that, in turn, are easily accessible from N-acyl-α-amino acids. Effective electrophilic activation of the α-position of 1-(N-acetylamino)alkylphosphonates was achieved by electrochemical α-methoxylation of these compounds in methanol

• alkoxylation or aryloxylation of this position [20][29][30]. As we demonstrated, electrophilic activation of the α-carbon of 1-aminophosphonates can easily be achieved by electrochemical α-methoxylation of these compounds in methanol, mediated with NaCl (Scheme 1, Table 2). α-Methoxylations were carried out in

• methyltriphenylphosphonium iodide in similar Michaelis–Arbuzov-like reactions of 1-(N-acylamino)alkylphosphonium salts was explained in our previous paper [47]. Conclusion It was demonstrated that effective electrophilic activation of the α-position of 1-(N-acetylamino)alkylphosphonates can be achieved by electrochemical α

Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols

• Gadi Ranjith Kumar,
• Yalla Kiran Kumar,
• Ruchir Kant and
• Maddi Sridhar Reddy

Beilstein J. Org. Chem. 2014, 10, 1255–1260, doi:10.3762/bjoc.10.125

• very few recent methods [16][17][18][19][20][21][22][23], including ours [16], disclosed the utilization of internal nucleophiles for trapping the ketenimines successfully. In continuation of our interest in the functionalization of alkynes through electrophilic activation [24][25][26][27][28][29], we

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• point of view [33]. Although many metal and Brønsted acid assisted processes have been documented the high functional group tolerance of gold complexes combined with their high efficiency in the electrophilic activation of C–C multiple bonds have made gold catalysis an important tool for the

• and high enantioselectivity (Table 2). 4 Formation of C–C bonds Besides heteroatoms, the electrophilic activation of alkenes by gold catalysts can be exploited also to form new C–C bonds. Early achievements relied on the use of active methylene compounds or electron rich arenes as carbon nucleophiles

• )] intermediate 161 and regenerating the [Ru(II)(bpy)3]2+ photocatalyst. Finally, arylated tetrahydrofuran 158 was obtained by reductive elimination with concomitant regeneration of the [Au(I)] catalyst. Conclusion Metal catalyzed electrophilic activation of isolated alkenes is by far considered among the most

Re₂O₇-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles

• Wantanee Sittiwong,
• Michael W. Richardson,
• Charles E. Schiaffo,
• Thomas J. Fisher and
• Patrick H. Dussault

Beilstein J. Org. Chem. 2013, 9, 1526–1532, doi:10.3762/bjoc.9.174

• dimers may be the predominant precursors of the perrhenate intermediates and therefore the reaction products (Scheme 3). The results with peroxyhemiacetals are consistent with the known reactivity of bisperoxyacetals [26]. The hydroperoxyacetals showed no sign of electrophilic activation of the

• presence of Re2O7 [15]. Conclusion Perrhenates hold broad potential as catalysts for electrophilic activation of hemiacetals. The ability to catalyze formation of O,O-, O,S-, and S,S-acetals under very mild conditions offers a useful complement to traditional Brønsted acid catalysts. Transacetalization 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

• communication describes a metal-catalyzed directed electrophilic C–H activation of an electron-rich Cp ring of ferrocene. Pentamethylcyclopentadienyl (Cp*)Rh(III) is known to catalyze electrophilic activation of aryl C–H bonds, typically in the presence of an acetate ligand, and is used for oxidative C–C-bond

• imines, isocyanates, and aldehydes by directed electrophilic activation of aryl C–H bonds at relatively low temperature and under oxidant-free conditions [15][16][17][18][19][20][21]. We also reported that cationic Cp*Ir(III) complexes, combined with 1 equiv/Ir of Cu(OAc)2, catalyzed the directed C–H

Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

• Sergio Pascual,
• Christophe Bour,
• Paula de Mendoza and
• Antonio M. Echavarren

Beilstein J. Org. Chem. 2011, 7, 1520–1525, doi:10.3762/bjoc.7.178

• synthesis of two functionalized decacyclenes in a one-pot transformation in which three C–C bonds are formed with high efficiency. Keywords: alkynes; gold(I) catalysis; hydroarylation; polyarenes; Introduction Electrophilic activation of alkynes in functionalized substrates by gold catalysts allows for

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

When gold can do what iodine cannot do: A critical comparison

• Sara Hummel and
• Stefan F. Kirsch

Beilstein J. Org. Chem. 2011, 7, 847–859, doi:10.3762/bjoc.7.97

• matched by electrophilic activation modes, or ii) leads to different product frameworks on treatment with electrophiles. The focus is put on alkyne activation only, while related processes based on the activation of alkenes and allenes are not covered in this review. Review Heterocyclization The vast

• reaction does not occur via electrophilic activation. Instead, due to the iodide ion still present in the reaction mixture, the ammonium ion intermediate undergoes SN1 or SN2 substitution, or even E2 elimination of an alkyl group. This system yields products in up to quantitative yields, and successfully

Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

• Paul W. Davies,
• Nicolas Martin and
• Neil Spencer

Beilstein J. Org. Chem. 2011, 7, 839–846, doi:10.3762/bjoc.7.96

• other reports into π-acid promoted alkynyl aziridine cycloisomerisations without skeletal rearrangement [20][21][22][23]. Our working mechanism to explain this reaction divergence centred on the electrophilic activation of the alkyne in A triggering a ring-expansion to a common intermediate B from which

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• were screened and it was found that DBU not only inhibited the isomerization of vinylcyclopropene 18 in the presence of AgOTf, but also led to a completely regioselective gold-catalyzed process to afford indene 19 as the sole reaction product (97%) (Scheme 10) [20]. Upon electrophilic activation

• once the rearrangement was complete. For substrates 29 possessing an unsymmetrically substituted endocyclic olefin, it is worth noting that electrophilic activation of the cyclopropene occurred regioselectively to produce the organogold species 31 (formally resulting from the ring-opening of a

• mixtures of the inseparable regioisomeric indenes 36b–36d and 36’b–36’d. Electrophilic activation and ring-opening of cyclopropenes 34 favored the formation of the organogold species 37b–37d. Furanones 35b–35d and indenes 36b–36d result from nucleophilic attack on these latter intermediates at C1 by the

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• introduction of the aziridine via the olefinic portion of a pyrroline such as 74 [82]. The construction of this compound would proceed through a sequence such as that depicted in Scheme 21. Upon electrophilic activation of the olefin 75, the aniline would attack it to form a pyrroline ring, making the terminal