Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• –Jung vinylsilane reagents 33. Kawamura et al. performed zinc enolate trapping reactions using ligand L10, a chiral quinoline-based N,N,P-ligand (Scheme 8A) [35]. The authors have concluded that the strict control of the amount of organozinc reagent added is essential to avoid side-product formation

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• a diminution in yield was observed when the amount of vinylsilane was decreased to 1.5 equivalents (Table 2, entry 3). The flow alkylation reaction thus appeared to be as efficient with a 1 mol % catalyst loading as with 5 mol %, in contrast to the batch conditions which required 5 mol % of the

Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines

• Matthew J. Fleming and
• David M. Hodgson

Beilstein J. Org. Chem. 2021, 17, 2385–2389, doi:10.3762/bjoc.17.155

• )trimethylsilane (13) [17], gave vinylsilane 14 (26%, E/Z = 81:19) on reaction with terminal epoxide 5 in the presence of LTMP (Scheme 6); the allylic alcohol 6 was also isolated (20%), suggesting that in our hands lithium–trimethylsilyl exchange competes with lithiation of (methoxymethyl)trimethylsilane (13

• epoxide 5. Synthesis of vinylsilane 14. Allylic alcohol 8 from epoxide 5 and sulfone 15. Allylic amines from aziridine 17. Cyclopropylidene synthesis from aziridine 20. Cinnamylamine 23 synthesis from aziridine 17. Cinnamylamine 23 synthesis from isopropyl or neopentyl benzylic ethers 26 and 27

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• ]. Similar to Prins cyclization of allylsilanes, Dobbs and co-workers recently utilized the corresponding vinylsilane as an alternative for the synthesis of cis-2,6-dihydropyran [89][90]. The synthesis involves tandem addition of vinylsilane, followed by silyl-Prins cyclization reaction. For example, 4

• . A similar tandem strategy of an addition of vinylsilane 196, followed by silyl-Prins cyclization with an aldehyde 197 in the presence of 5 mol % BiBr3, was reported by Hinkle and co-workers to give the corresponding compound 198 (Scheme 47) [18]. The authors further investigated the Mukaiyama aldol

• mechanism similar to simple Prins cyclization, except trapping of oxocarbenium ion 214 with silyl enol ether instead of olefin, vinylsilane, or allylsilanes, was proposed as shown in Scheme 51. However, the reaction of silyl enol ether such as 216, upon reacting with an unsaturated aldehyde 217, produced a

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• of the vinylsilane cycloaddition to the Ru=C bond. The knowledge of this untypical reactivity is pivotal for the application of metathesis for the modification of vinylsilanes, vinyl-substituted siloxanes, spherosilicates and silsesquioxanes. The appropriate choice of substituents permits the control

• of the postulated complex C with vinylsilane gives the corresponding (E)-1,2-bis(silyl)ethenes and the methylene complex B. The methylene complex B may react with vinylsilane to form ethene and regenerate complex C. In the presence of vinylsilanes containing alkyl substituents the Grubbs catalyst

• converted in metathesis is worth noting as the analogous vinylsilane does not undergo metathesis. In 2010 Laine reported a procedure enabling the synthesis of polyhedral vinylphenyl-substituted deca- and dodecasilsesquioxanes (denoted T10 and T12, respectively) [25]. Divinyl octa- or decaphenylsubstituted

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation

• Gisela V. Saborit,
• Carlos Cativiela,
• Ana I. Jiménez,
• Josep Bonjoch and
• Ben Bradshaw

Beilstein J. Org. Chem. 2018, 14, 2597–2601, doi:10.3762/bjoc.14.237

• stereoselectivity of the ring-formation step can be explained by the suprafacial addition of the allene to the double bond of the α,β-unsaturated compound 4, the diastereoselectivity being sterically controlled by the methyl group on the β-face. The transformation of the vinylsilane moiety in 5 into the

• corresponding carbonyl group (Scheme 4) was carried out by a two-step procedure involving epoxidation of the vinylsilane 5, followed by a rearrangement of the diastereomeric mixture of epoxides 7 induced by formic acid [34][35]. The resulting ketone 8 was obtained as a 3.5:1 mixture of epimers at C3. The

• of the vinylsilane moiety to ketone 8. Supporting Information Supporting Information File 358: Experimental procedures and copies of 1H and 13C NMR spectra of all compounds. Acknowledgements Financial support for this research was provided by Project CTQ2016-41338-P and CTQ2013-40855-R from the

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• yields via Peterson olefination through a silylated betaine 16. The alternatively possible Wittig reaction to vinylsilane 18 can be considered as a side reaction (Scheme 11) [17][18]. The transformation shown in Scheme 11 was proven to be a general reaction with the possible participation of both

Base-promoted isomerization of CF₃-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions

• Yoko Hamada,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 1507–1512, doi:10.3762/bjoc.13.149

• work is considered to draw a clear line with these instances because of the apparently convenient metal-free process. Moreover, the same type of proton shift has also reported by two groups. For example, during the reaction of (E)-2-(trifluoromethyl)vinylsilane and benzaldehyde in the presence of an

C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation

• Zhenhua Ding and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2012, 8, 1536–1542, doi:10.3762/bjoc.8.174

• with a vinylsilane was achieved by using a cobalt catalyst generated in situ from CoBr2, bathocuproine, and cyclohexylmagnesium bromide. The reaction allows coupling between a series of N-pyrimidylindoles and vinylsilanes at a mild reaction temperature of 60 °C, affording the corresponding alkylated

• indoles in moderate to good yields. Keywords: alkylation; C–H functionalization; cobalt; indole; vinylsilane; Introduction The indole ring ubiquitously occurs in biologically active natural and unnatural compounds [1][2][3]. Consequently, there has been a strong demand for catalytic methods allowing

• alkylation of N-pyrimidyl indole 1a with vinylsilane 2a In a Schlenk tube were placed 1-(pyrimidin-2-yl)-1H-indole (1a) (58.6 mg, 0.3 mmol), CoBr2 (6.6 mg, 0.03 mmol), and bathocuproine (10.8 mg, 0.03 mmol), which were then dissolved in THF (1.3 mL). To the solution was added cyclohexylmagnesium bromide

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• to that of the zinca-Claisen reaction observed by Suzuki and co-workers [38]. Analogous to the previous work in our group [15], the silyl-substituted allene 16 produced the (E)-vinylsilane 17 as the sole product in this reaction. Given the success of the one-pot intermolecular reductive coupling of

Recent advances in carbocupration of α-heterosubstituted alkynes

• Ahmad Basheer and
• Ilan Marek

Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77

• undergoes a subsequent thermal [3,3]-sigmatropic rearrangement to give the corresponding nitrile 27. The presence of the organomagnesium group on 26 is essential for the rearrangement to proceed in good yield (Scheme 12). The silylcupration of N-1-alkynylsulfonylamides 28 led to the desired vinylsilane

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

• %) and some reduced adduct 18b (12%, entry 2). Interestingly, addition of xanthate 1a to allylsilane 9 gave adduct 19a in a high yield (71%, entry 3), while addition of xanthate 1a to vinylsilane 10 afforded adduct 20a (57%, entry 4). Reaction of xanthate 1a with allylboronate 11 gave compound 21a in a

Single and double stereoselective fluorination of (E)-allylsilanes

• Marcin Sawicki,
• Angela Kwok,
• Matthew Tredwell and
• Véronique Gouverneur

Beilstein J. Org. Chem. 2007, 3, No. 34, doi:10.1186/1860-5397-3-34

• for which the relative stereochemistry was unambiguously identified by X-ray analysis.[31] This line of conjecture allowed us to verify our stereochemical assignments. We investigated the feasibility of the double fluorination with (E)-allylsilane 4 prepared from (E)-vinylsilane 5 [33] via a [3][3

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• substituted cyclobutenes after cyclization of the vinylsilane or vinylstannane intermediate. [23] Cyclization of the corresponding vinylsilanes gave poor results of no synthetic utility, however the vinylstannane strategy results in formation of 1- and 3-substituted cyclobutenes 42 and 43 in good yield

• , we showed that α,β-unsaturated nitriles undergo a double addition process when treated with the cuprate species resulting from addition of 1 to allene, giving ketones 44 containing both an allylsilane group and a vinylsilane moiety (Scheme 10). [24] Equilibration between species 2 and 45 as the

• before (see Scheme 3), gives chemoselectively methylenecyclopentanols, while the vinylsilane unit remains unchanged (Scheme 10). [24] Recent work revealed that addition one equivalent of organolithium reagent (R1Li) to the reaction mixture leads to the formation of ketones of type 46 (Scheme 10), which

Synthesis of 2,6-trans- disubstituted 5,6-dihydropyrans from (Z)-1,5-syn-endiols

• Eric M. Flamme and
• William R. Roush

Beilstein J. Org. Chem. 2005, 1, No. 7, doi:10.1186/1860-5397-1-7

• ) ring closing metathesis,[12][13] (iv) vinylsilane cyclization of oxocarbenium ions,[14] and (v) intramolecular allylations.[15][16] However, we were unaware of any reports that describe the direct conversion of 1,5-diols containing an internal olefin such as 2 directly to 2,6-trans-disubstituted 5,6