Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• corresponding 1,2,3-cyclopropenium bromides was realized by a classical approach: combination of C1 and C2 building blocks, i.e., the addition of a carbene species to a triple bond of diarylacetylene, followed by treatment of the produced cyclopropene with HBr to convert it to the corresponding cyclopropenylium

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• [15]. In our recent studies, great attention was paid to developing methods for the synthesis of spiro[3-azabicyclo[3.1.0]hexanes] based on 1,3-dipolar cycloaddition reactions involving azomethine ylides and cyclopropene dipolarophiles, and also the in vitro activity of some synthesized compounds has

• and cannot be isolated as individual compounds. At the same time, the reaction of ninhydrin and proline results in the formation of the stable azomethine ylide. This 1,3-dipole demonstrated high reactivity towards diverse cyclopropenes, including parent cyclopropene [22]. Note that the reactions of

• synthetic potential of PRP only on the basis of this study. Positioning the current study as a continuation of a series of our works, in which cyclopropenes are utilized as dipolarophiles, we have described a synthetic route to bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane through cyclopropene

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• stereoselective methods for the synthesis and transformations of cyclopropane derivatives. These investigations gained a significant interest, because cyclopropane and cyclopropene fragments are present in the structures of many biologically active substances, such as antibiotics, anticancer, and antimycotic

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• selectivity of simple alkenes. In this regard, most examples have been restricted to the use of ethylene or strained alkenes such as cyclopropene, norbornene, norbornadiene, (E)-cyclooctene, or bicyclo[3.2.0]hept-6-ene [67][68][69]. The first example of an intermolecular version of fluorinated compounds was

• specifically the Hashimoto catalyst ([Rh2(S-TCPTTL)4]) was found to be the most efficient in terms of yield and enantioselectivity. In this study, the authors described an example of an intermolecular PKR using the strained difluoromethylated cyclopropene 73 which, upon reaction with the hexacarbonyldicobalt

• reported by the group of Helaja [80]. Intermolecular PKR reported by León and Fernández [81]. PKR reported with cyclopropene 73 [82]. Acknowledgements We thank the authors of the papers collected here for the hard work that made this review possible. The authors also thank Joel Navarro and Marta Pons for

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• Marwan Simaan Ilan Marek The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 32000, Israel 10.3762/bjoc.15.71 Abstract The diastereoselective carbocupration reaction of alkoxy-functionalized cyclopropene derivatives

• (or amination) sequence on achiral nonfunctionalized cyclopropenes provided the desired cyclopropanol (and cyclopropylamine) derivatives in excellent diastereo- and enantiomeric excesses. Keywords: carbocupration; cyclopropanol; cyclopropene; regioselectivity; stereoselectivity; Introduction The

• be addressed carefully as it plays an important role in the control of the regioselectivity of the reaction pathway. An alkyl group on the C1 position of the cyclopropene should control the regioselectivity of the addition of the organometallic species to give the more stable secondary

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• glycoengineering (MGE). They readily react with tetrazines in an inverse electron-demand Diels–Alder (DAinv) reaction, a prime example of a bioorthogonal ligation reaction, allowing their visualization in biological systems. Here, we present a comparative study of six cyclopropene-modified hexosamine derivatives

• and their suitability for MGE. Three mannosamine derivatives in which the cyclopropene moiety is attached to the sugar by either an amide or a carbamate linkage and that differ by the presence or absence of a stabilizing methyl group at the double bond have been examined. We determined their DAinv

• norbornenes, have high DAinv reaction kinetics, but suffer from low incorporation efficiencies [21]. Cyclopropenes, that combine fast reaction kinetics and small size, turned out to be excellent reporters for application in MGE [22][23][24][25][26][27]. Three cyclopropene-derivatized mannosamine derivatives

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• transformations include the carboxylation of a (trimethylsilylmethyl)cyclopropene in the presence of a fluoride promoter [22], and also the addition of electrophiles to (lithiomethyl)cyclopropenes generated by lithiation of the corresponding methylcyclopropenylsulfone [23] or -sulfoxide [24]. More recently, the

• cyclopropenylcarbinols led to the corresponding phosphine oxides 3d–h (85–93%) as a 80:20 mixture of E/Z geometric isomers, regardless of the substituent of the alcohol (at C4) and of the cyclopropene (at C2, Scheme 2) [33][34]. The [2,3]-sigmatropic rearrangement of an optically enriched phosphinite 2f, prepared from

• phosphinite 6a which afforded a 73:27 mixture of the diastereomeric phosphine oxides 7a/7’a (86%). The major diastereomer 7a corresponds to a sigmatropic rearrangement occurring on the most hindered face (cis to the aromatic group) of the cyclopropene which was somewhat surprising. Substitution at the para

Synthesis of 1,2-divinylcyclopropanes by metal-catalyzed cyclopropanation of 1,3-dienes with cyclopropenes as vinyl carbene precursors

• Jesús González,
• Alba de la Fuente,
• María J. González,
• Laura Díez de Tejada,
• Luis A. López and
• Rubén Vicente

Beilstein J. Org. Chem. 2019, 15, 285–290, doi:10.3762/bjoc.15.25

• reagents (Scheme 1d). Herein, we present the results of this study. Results and Discussion At the outset, the reaction of cyclopropene 1a and freshly distilled 1,3-cyclohexadiene (2a, 5.0 equiv) in the presence of ZnCl2 as catalyst was performed under the reaction conditions previously employed for simple

• 3c only when ZnCl2 was used as catalyst (85%, endo/exo = 4.5:1) at slightly higher temperature (50 °C). In this case, [Rh2(OAc)4] completely failed under different reaction conditions leading inevitably to degradation of starting cyclopropene. Other cyclic 1,3-dienes were then evaluated. For instance

• substituted alkene, allowing the synthesis of 1,2-divinylcyclopropane 3k within the typical range of yields and cis/trans selectivities. Finally, 1,2,3-trisubstituted divinylcyclopropane 3l was prepared in 50% (cis/trans = 2.5:1) from cyclopropene 1a and (1E,3E)-1,4-diphenylbuta-1,3-diene through a

The synthesis of functionalized bridged polycycles via C–H bond insertion

• Jiun-Le Shih,
• Po-An Chen and
• Jeremy A. May

Beilstein J. Org. Chem. 2016, 12, 985–999, doi:10.3762/bjoc.12.97

• substrates with a 3-atom tether to the hydrazone and sterically large substituents allowed the isolation and characterization of mechanistic intermediates from the cascade reaction when it was conducted at 90 °C (Scheme 21). This confirmed some prior proposals of a cyclopropene intermediate [92], as the

• cyclopropene 97 reacted [93][94] to form the same products as the hydrazone 96 did directly when heated to 140 °C. Gold The work by the May group was soon followed by gold-promoted carbene/alkyne cascades. These cascades rely on Zhang’s discovery that the use of pyridine N-oxides allow for the formation of

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• related to the RRM readers may refer to excellent reviews available in the literature [3][4][5][6]. Review Cyclopropene systems Cyclopropene derivatives are highly strained systems and they are ideal candidates for the RRM process. In this context, Zhu and Shi [7] have reported the ring-closing enyne

• with the aid of a carbene insertion reaction. Further, this cyclopropene system 16 was subjected to RRM in the presence of catalyst 1 to generate 3-pyrroline derivatives 18a,b using simple starting materials in a single step (Scheme 1). A wide range of heterocycles have been assembled by RRM. When a

• substituted cyclopropene such as 19 (or 20) was treated with catalyst 2 in the presence of ethylene (24) the required heterocycle 22 (or 23) was obtained in moderate to good yield (Scheme 2) [8]. Allyl ethers 25a,b and 26a,b were reacted with catalyst 2 to deliver the corresponding dihydrofurans (27a,b and

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• cannot take place because of steric hindrance by the gem-dimethyl group. Intermediate 15 is a vinylcarbene that, in principle, has several options to react further. It could dimerize to the intended product 14 (or its diastereomer), cyclize to a cyclopropene derivative or react via its resonance

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• Diels–Alder reaction between methylcyclopropene tags and tetrazines has become a popular ligation reaction due to the small size and high reactivity of cyclopropene tags. Attaching the cyclopropene tag to mannosamine via a carbamate linkage has made the reaction even more efficient. Here, we expand the

• application of cyclopropene tags to N-acylgalactosamine and N-acylglucosamine derivatives enabling the visualization of mucin-type O-glycoproteins and O-GlcNAcylated proteins through Diels–Alder chemistry. Whereas the previously reported cyclopropene-labeled N-acylmannosamine derivative leads to significantly

• are small enough to be accepted by cellular enzymes during MOE [22][23][24]. Also, they are stable in aqueous solution in the presence of biological nucleophiles [22][28]. Consequently, cyclopropene tags were attached by an amide linkage to sialic acid [22] and ManNAc derivatives including Ac4ManNCyc

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• copper-catalyzed reaction of cyclopropene 3a with methylmagnesium reagent to afford 3b with perfect stereoselectivity (Scheme 19) [84]. Not only methylmagnesium reagents but also vinyl- or alkynylmagnesium reagents could be employed. Although the arylation reaction did not proceed under the same

• al. improved their copper-catalyzed carbometalation reactions of cyclopropenes by using functional-group-tolerable organozinc reagents (Scheme 22) such as dimethyl-, diethyl-, diphenyl-, diisopropyl-, and divinylzinc reagents [91]. Treatment of cyclopropene 3d with dimethylzinc in the presence of a

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

• intramolecular hydroalkoxylation was reported by Zhang and co-workers [30]. A tandem cyclization mechanism was proposed by the authors. The first example of gold-catalyzed ring-opening addition of cyclopropenes has been developed by Lee’s group [31][32]. The reaction of alkyl-disubstituted cyclopropene 36 with a

• indenes 40 is observed upon introduction of ester and phenyl substituents on the cyclopropene (Scheme 7). AuPR3NTf2 complexes (PR3 = 41–45) are selective catalysts for the intermolecular hydroalkoxylation of electron-poor alkynes of type R−C≡C−EWG and dimethyl acetylenedicarboxylate [33]. In reactions of

• (Z)-acetoxydienes [48]. Thus, treatment of 4-nitrobenzaldehyde derived cyclopropene 90 with a catalytic amount of PPh3AuNTf2 in DCM led to quantitative formation of acetoxy diene 91 with a 4:1 Z:E selectivity within 5 min at −50 °C. Wang et al. developed an efficient method for the preparation of

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• activation of the cyclopropene, cation 55 is formed. C–C bond cleavage of the cyclopropyl ring followed by a Friedel–Crafts reaction affords, after recovery of aromaticity, the observed products [47]. 4 Ring expansions involving annulation reactions Diels–Alder, [1,3]-dipolar-, [2 + 2]- and [4 + 3

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

• reactions involving cyclopropenes among which the addition of alcohols to 3-methyl-3-nonylcyclopropene (8) was investigated in detail [18]. A variety of primary alcohols reacted with cyclopropene 8 in the presence of either in situ generated [(Ph3P)AuOTf] or [(Ph3P)AuNTf2] (5 mol %) to afford the

• species 12, generated by electrophilic ring-opening of cyclopropene 8, followed by protodeauration of the resulting vinyl gold species 13. Using CD3OD as a nucleophile effectively led to 90% deuterium incorporation at C1 and formation of a mixture of geometric isomers (Scheme 7) [18][19]. Interestingly

• dependent and did not operate in the presence of the NHC–gold complex [(IPr)AuOTf]. Thus, when cyclopropene 8 was treated with a stoichiometric quantity of EtOH in the presence of the latter catalyst (5 mol %), the tertiary allylic ether 9a was obtained with high regioselectivity (>99:1), but the yield (51

The allylic chalcogen effect in olefin metathesis

• Yuya A. Lin and
• Benjamin G. Davis

Beilstein J. Org. Chem. 2010, 6, 1219–1228, doi:10.3762/bjoc.6.140

• stereoselective ring-opening cross-metathesis (ROCM) (Scheme 5) [24]. The activating effect from the allylic hydroxy group in metathesis is prominent in this example. The ROCM of cyclopropene 13 with enantiomerically enriched allylic alcohol 14a is complete in 5 minutes (>98% conversion) with a high

• coordination of the cyclopropene to the catalyst, the formation of a metallacyclobutane such as 15 with the larger R group pointing away from the main bulk of the catalyst is preferred (Scheme 5b). This intermediate then collapses to give the product with the observed stereoselectivity. Sasaki and co-workers

Part 3. Triethylborane- air: a suitable initiator for intermolecular radical additions of S-2-oxoalkyl- thionocarbonates (S-xanthates) to olefins

• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 47, doi:10.1186/1860-5397-3-47

• Et3B as a radical initiator at 0°C for the intermolecular addition of an S-alkylxanthate onto 1,1-dimethoxy-2-cyclopropene, has been mentioned in the literature but without success.[5][6] In part 1 of this series, we reported that trialkylboranes are convenient reagents, when used in excess, to reduce