Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• and epoxides, hydrohalogenation (HCl, HBr addition), halogenation (Br2 and I2 addition), and [2 + 2] cycloaddition with chlorosulfonyl isocyanate. The resulting adducts were fully characterized by spectroscopic and analytical methods; they constitute interesting substrates for further organic

• takes place by a radical or an ionic mechanism. Addition of chlorosulfonyl isocyanate to 2 The addition of heterocumulenic systems to several allenes has been studied previously. For instance, Moriconi and Kelly added chlorosulfonyl isocyanate (CSI, 66) to monoallenes, such as tetramethyallene (65, 2,4

• 67, which subsequently either ring-closes to 68 or is converted into 69 by proton loss and hydrolysis of the chlorosulfonyl group. When the bisallene 2 was treated with 66 (1 equiv) at 0 °C the cycloaddition was complete after ca. 4 h as shown by monitoring the isocyanate band at 2260 cm−1 in the IR

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

• activation of aryl C–H bonds at room temperature [23]. In this manuscript, we report application of this nonoxidative Rh(III) catalysis to synthesize planar chiral 1,2-disubstituted ferrocene derivatives. Results and Discussion We chose the reaction of ferrocenyl imine 1a and phenyl isocyanate as a model

• [RhCp*(OAc)2(H2O)] along with a slight decrease of yield (Table 2, entry 1). Both electron-rich and -poor aryl isocyantes showed similar reactivity in the present reaction (Table 2, entries 2 and 3). The use of benzyl isocyanate also formed the monoamidated product 2d (Table 2, entry 4). It required a

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• ) imide [42]. Formal [2 + 2] cycloaddition of methyl isocyanate at a ruthenium silylene [58]. Oxygen-atom transfer from phenyl isocyanate to a cationic terminal borylene [60]. Coupling of a phosphorus ylide with an iridium methylene [62]. Reactions of (PNP)Ir═C(H)Ot-Bu with oxygen-containing

Approaches to α-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

• Sosale Chandrasekhar and
• V. Mohana Rao

Beilstein J. Org. Chem. 2012, 8, 1393–1399, doi:10.3762/bjoc.8.161

• corresponding methyl carbamates 10 were obtained in excellent yields (Table 3). The reaction may well occur via the putative N-acetoxy derivative I (up to now this has not been proven). The in situ trapping of the expected isocyanate intermediate (not shown) by methanol would explain the final formation of 10

Synthesis and biological evaluation of nojirimycin- and pyrrolidine-based trehalase inhibitors

• Davide Bini,
• Francesca Cardona,
• Matilde Forcella,
• Camilla Parmeggiani,
• Paolo Parenti,
• Francesco Nicotra and
• Laura Cipolla

Beilstein J. Org. Chem. 2012, 8, 514–521, doi:10.3762/bjoc.8.58

• isocyanate in dimethoxyethane at 85 °C afforded urea 23 (15% yield over two steps). Reaction of compound 24 directly with benzyl isocyanate in dimethoxyethane at 85 °C afforded urea 25 in 72% yield (Scheme 1B). The hydrogenolysis of benzyl ureas 23 and 25 unexpectedly proceeded in a different manner

• pyrrolidines 26 and 27 [22], by following the same synthetic steps used for nojirimycin derivatives, as outlined in Scheme 2. Direct hydrogenolysis of 26 and 27 afforded quantitatively the compounds 14 and 17, respectively. Cbz deprotection of 26 and 27 followed by reaction with benzyl isocyanate in

• used for the benzyl isocyanate reaction (see general procedure for details). General procedure for benzyl isocyanate reaction: To a 0.07 M solution of the appropriate compound dissolved in dry DME, benzyl isocyanate (2 equiv) was added and the reaction mixture was heated under reflux. After 2 h the

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• -allenylamines, organic halides and isocyanates [42]. In this process, there is first a carbopalladation of the functionalized allene with the aryl iodide, followed by reaction of the internal aza-nucleophile with the highly electrophilic isocyanate derivative, before premature trapping of the initially formed π

A novel high-yield synthesis of aminoacyl p-nitroanilines and aminoacyl 7-amino-4-methylcoumarins: Important synthons for the synthesis of chromogenic/fluorogenic protease substrates

• Xinghua Wu,
• Yu Chen,
• Herve Aloysius and
• Longqin Hu

Beilstein J. Org. Chem. 2011, 7, 1030–1035, doi:10.3762/bjoc.7.117

• condense with p-nitrophenyl isocyanate to form the Nα-protected aminoacyl-pNAs [14]. However, commercially available p-nitrophenyl isocyanate often contains impurities due to degradation during storage; these impurities must be removed before use. In addition, a significant amount of hydantoin by-product

Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives

• Heiko Ihmels and
• Jia Luo

Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37

• The bisureido- and bisthioureido-substituted dibenzobarrelene derivatives 1e–i were synthesized by the reaction of the known bis(diaminomethyl)-substituted derivative of dibenzobarrelene 1d [45] with a slight excess of the corresponding isocyanate or isothiocyanate (Scheme 3). The resulting products

• in front of the lamp. General procedure for the preparation of bisurea- and bisthiourea derivatives of dibenzobarrelene (GP1): The isocyanate or isothiocyanate derivative (1.1 molar equiv) was added to a stirred solution of 11,12-bis(aminomethyl)-9,10-dihydro-9,10-ethenoanthracene (1d, 0.45–10.0 mmol

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• palladium-catalyzed reaction. To test the proposed mechanism of this reaction, first, bicyclonorcarene endoperoxides derived from cyano and carbomethoxy cycloheptatrienes were synthesized and converted into the corresponding diols. The reaction of diols with toluenesulfonyl isocyanate followed by a

• consecutive reactions, i.e., the generation of 8 and a subsequent a stereospecific Pd(0)-catalyzed cyclization [3][4][5][20]. Thus, the ene-diol 7 was first treated with 2 equiv of toluenesulfonyl isocyanate to give the corresponding biscarbamate 8. A solution of biscarbamate 8 was then added to a 5% solution

• diacetates 15 and 18b. The isomeric diols 14 and 18a were treated with 2 equiv of toluenesulfonyl isocyanate as described above to give the corresponding biscarbamates 16 and 19. Treatment of 16 and 19 with the palladium catalyst (as described above) resulted in the formation of oxazolidinone derivatives 17

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• and sodium nitrite in water at 0–5 °C to provide an intermediate diazonium salt. The latter underwent cycloaddition with an isocyanate in a one-pot reaction to give compound 43 (Scheme 10) [41]. 5-Aminopyrazoles 45 have recently been prepared by Boc deprotection of the α-hydrazino acids 44 with TFA in

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• with 4-nitrophenyl isocyanate (obtained from 4-nitroaniline by reaction with triphosgene in dry THF) in dry THF to give urea derivative 5. Subsequent reaction of 5 with 9-chloromethylanthracene under refluxing conditions in dry CH3CN gave the chloride salt 6. Anion exchange of the salt 6 with NH4PF6

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• using functionalized monomers or copolymers with additional functionality that do not participate in the polyaddition, in this case, e.g., amino, carboxylic, hydroxy, epoxide, isocyanate, or isothiocyanate. Such capsules could be used to encapsulate contrast agents (Magnevist®, Gadovist®) for magnetic

Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration

• Latif Kelebekli,
• Yunus Kara and
• Murat Celik

Beilstein J. Org. Chem. 2010, 6, No. 15, doi:10.3762/bjoc.6.15

• diols in the presence of p-toluenesulfonyl isocyanate for the introduction of the amino alcohol functionality. We are currently interested in the synthesis of cyclitols and their derivatives [25]. As a part of our program directed towards the synthesis of potential glycosidase inhibitors we used a

• % yield. The introduction of the amino alcohol functionality was achieved by a regio- and stereoselective Pd(0) catalyzed reaction of diol 11 and TsNCO [32]. Thus treatment of the cis-diol 11 in THF with 2 equiv of p-toluenesulfonyl isocyanate gave the corresponding bis-carbamate 12 which was subsequently

• the peroxide bond in 20 with thiourea under very mild conditions gave the cis-diol 21 in 95% yield. Diol 21 in THF was treated with 2 equiv of p-toluenesulfonyl isocyanate to give the intermediate bis-carbamate 22 which was then treated as described above for 12 with the same Pd(0) catalyst to afford

A short synthesis of (±)-cherylline dimethyl ether

• Bhima Y. Kale,
• Ananta D. Shinde,
• Swapnil S. Sonar,
• Bapurao B. Shingate,
• Sanjeev Kumar,
• Samir Ghosh,
• Soodamani Venugopal and
• Murlidhar S. Shingare

Beilstein J. Org. Chem. 2009, 5, No. 80, doi:10.3762/bjoc.5.80

• Sciences and Humanities Department, SVNIT, Surat – 395 007, India 10.3762/bjoc.5.80 Abstract A synthesis of (±)-cherylline dimethyl ether is reported. The key steps involved are Michael-type addition, radical azidonation of an aldehyde, Curtius rearrangement, and reduction of an isocyanate intermediate

• are Michael addition, radical azidonation of aldehydes [18], Curtius rearrangement, and reduction of an isocyanate intermediate followed by Pictet–Spengler cyclization. Results and Discussion Our retrosynthetic analysis of (±)-cherylline dimethyl ether (5) is depicted in Scheme 1. It can be

• anticipated that 5 could be constructed via a Pictet–Spengler ring annulation from amine 6 which, in turn, could be obtained by reduction of the corresponding isocyanate. The required isocyanate would arise from the aldehyde 7 via radical azidonation followed by Curtius reaction. Lastly, aldehyde 7 could be

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

• the “normal” 5-substituted isoxazoline is formed. Hence, the nitrodecene 123 gives rise to only the nine-membered carbocycle 125 upon reaction with phenyl isocyanate. The matching HOMO-LUMO interactions for such cycloadditions favour the formation of 126 but ring strain and transannular steric effects

• sodium borohydride reduction of the remaining aldehyde, followed by alkylation of the resulting primary alcohol with methyl isocyanate to give 184. 6.4. Coleman. Allylation reaction and 1,4-quinone addition The Coleman group proposed an elegant synthesis of an enantiomerically pure mitosane. One of the

A facile synthesis and fungicidal activities of 2-(alkylamino)-5,6-dimethylthieno[2,3-d]pyrimidin- 4(3H)-ones

• Yang-Gen Hu,
• Ai-Hua Zheng,
• Xu-Zhi Ruan and
• Ming-Wu Ding

Beilstein J. Org. Chem. 2008, 4, No. 49, doi:10.3762/bjoc.4.49

• isocyanate (2 mmol) under nitrogen at room temperature. After the reaction mixture was stirred for 6–12 h at 0–5 °C, the solvent was removed under reduced pressure and ether/petroleum ether (1:2, 20 mL) was added to precipitate triphenylphosphine oxide. After filtration, the solvent was removed to give