Palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides

• Tao Fan,
• Wei-Dong Meng and
• Xingang Zhang

Beilstein J. Org. Chem. 2017, 13, 2610–2616, doi:10.3762/bjoc.13.258

• , Shanghai 200032, China 10.3762/bjoc.13.258 Abstract An efficient palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides has been developed. The reaction proceeds under mild reaction conditions with high efficiency and excellent functional group tolerance, even towards

• formyl and hydroxy groups. Preliminary mechanistic studies reveal that a secondary trifluoromethylated alkyl radical is involved in the reaction. Keywords: alkenes; cross-coupling; Heck-type reaction; palladium; secondary trifluoromethylated alkyl bromides; Introduction With the increasing number of

• radical via a single electron transition (SET) pathway is involved in the reaction. Inspired by this work, we question that whether secondary fluoroalkylated alkyl bromides are also suitable substrates for such a Heck-type reaction. To the best of our knowledge, the palladium-catalyzed Heck-type reaction

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• ], and different alkyl halides 3. Table 3 comprises the results obtained from the reaction of phenylacetylene (6a) with different alkyl halides 3. The reaction of primary alkyl bromides afforded the corresponding alkynyl selenide 5 in moderate to good yields. It is worth mentioning, that replacing n

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• method is based on biaryl cross-coupling between the sodium salt of the terephthalonitrile dianion and a neutral aromatic nitrile in liquid ammonia, and successive alkylation of the long-lived anionic intermediate with alkyl bromides. The reaction is compatible with benzonitriles that contain methyl

• , methoxy and phenyl groups, fluorine atoms, and a 1-cyanonaphthalene residue. The variety of ω-substituted alkyl bromides, including an extra bromine atom, a double bond, cyano and ester groups, as well as a 1,3-dioxane fragment are suitable as alkylation reagents. Keywords: alkylcyanobiaryls; cross

• shown by the example of alkylation of anion 3 arising from the sodium salt of 12− and benzonitrile 2a cross-coupling by alkyl bromides 6b–f that were functionalized at their terminal position with a double bond (6b) [33], an extra bromine atom (6c) [34][35], a cyano (6d) or ester group (6e), and a 1,3

Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

• Bijay Shrestha and
• Ramesh Giri

Beilstein J. Org. Chem. 2015, 11, 2400–2407, doi:10.3762/bjoc.11.261

• with alkyl bromides, which are more readily available and less expensive than alkyl iodides, required 10 mol % of NN-1/CuI (Table 2, entries 4–15). The reaction can be performed with electron-neutral and electron-rich triarylaluminum reagents [45]. The reaction tolerates a variety of functional groups

• ). Alkyl halide (1.0 mmol), CuI (1.9 mg, 0.010 mmol, for alkyl iodides; 19.0 mg, 0.10 mmol, for alkyl bromides) and NN-1 (1.6 mg, 0.010 mmol, for alkyl iodides; 16.4 mg, 0.10 mmol, for alkyl bromides) were then added to the solution of the triarylaluminum reagent. The reaction mixture was then tightly

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• a halide atom. This general scheme is outlined in Scheme 8. In 2013, Nishikata and co-workers reported that a copper/amine catalyst system catalyzes the alkenylation of tertiary alkyl bromides bearing an electron-withdrawing group [32]. As with many ATR reactions, multi-dentate amines were critical

• , internal alkenes (such as 39) were not affected during the reaction. Although the reaction proceeds via a distinct mechanism, the authors refer to the transformation as a formal Heck-type alkenylation of alkyl bromides. As with the nitroalkane alkylation chemistry illustrated above, this reaction is a rare

• alkene leading to the Z product (Scheme 12). After cross coupling, the ester can be hydrolyzed to provide exclusively the Z-alkene product (Scheme 13). This protocol is complementary to the initially reported alkenylation of tertiary alkyl bromides, which resulted exclusively in E-alkene products. When

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

Postsynthetic functionalization of glycodendrons at the focal point

• Thisbe K. Lindhorst and
• Katharina Elsner

Beilstein J. Org. Chem. 2014, 10, 1482–1487, doi:10.3762/bjoc.10.152

• employing long chain alkyl bromides. Williamson etherification of 4 using tetradecanyl bromide led to 10 in only 33% yield, and the same reaction starting with the primary alcohol 6 led to 11 in a somewhat better yield of 44% (Scheme 2). When the tetravalent glycodendron 3 was employed in the same

One-pot synthesis of cyanohydrin derivatives from alkyl bromides via incorporation of two one-carbon components by consecutive radical/ionic reactions

• Shuhei Sumino,
• Akira Fusano,
• Hiroyuki Okai,
• Takahide Fukuyama and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2014, 10, 150–154, doi:10.3762/bjoc.10.12

• forming reaction of alkyl bromides, CO and ethyl cyanoformate (Scheme 1, reaction 2). Results and Discussion We examined AIBN-induced radical formylation of 1-bromooctane (1a) with Bu3SnH under 80 atm of CO pressure in the presence of a cyanide source (Scheme 2). Under the employed conditions, the

• , the yield of 3a increased to 79%. We examined various alkyl bromides 1 in the present radical/ionic three-component coupling reaction (Table 1). Primary alkyl bromides 1b–e containing a chlorine atom, an ester group, a cyano group, or a phenyl group worked well to give the corresponding cyanohydrin

• derivatives 3b–e in good yields (Table 1, entries 2–5). The reaction of secondary and tertiary alkyl bromides 1f–i also proceeded well to give the corresponding cyanohydrins 3f–i in good yields (Table 1, entries 6–9). The reaction using cyclopropylmethyl bromide (1j) afforded the lowest yield of cyanohydrin

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• a one-pot, sequential synthesis of urea derivatives from alkyl bromides. With the aim to verify the feasibility of the method under conventional heating, the protocol was tested in a Parr reactor (90 mL) for an easier scale-up. Results and Discussion The Staudinger–aza-Wittig reaction is extremely

• . Conclusion In conclusion, a MW-assisted, one-pot sequential protocol for the synthesis of urea derivatives from alkyl bromides has been described. This study has proven that in acetonitrile under high CO2 pressure the Staudinger–aza-Wittig reaction in presence of PS-PPh2 is strongly promoted. Excellent

The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow

• Kimberley A. Roper,
• Malcolm B. Berry and
• Steven V. Ley

Beilstein J. Org. Chem. 2013, 9, 1781–1790, doi:10.3762/bjoc.9.207

• selection of alkyl bromides in high yield and purity without further off-line purification protocols. It was also shown that a single monolith could be used sequentially for Ramirez reactions and then the Appel reaction, but not in reverse order. This indicates that the Appel reaction consumes the Ramirez

• and ketones containing electron-withdrawing groups converted to the corresponding gem-dibromides using the triphenylphosphine monolith in flow. Alkyl bromides prepared from the corresponding alcohols using the triphenylphosphine monolith for the Appel reaction in flow. Supporting Information

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

• Yuta Nishina,
• Bunsho Ohtani and
• Kotaro Kikushima

Beilstein J. Org. Chem. 2013, 9, 1663–1667, doi:10.3762/bjoc.9.190

• useful bromide-containing precursors. For instance, alkyl alcohols can be converted to alkyl bromides in the presence of CBr4 and triphenylphosphine; this is known as the Appel reaction [28]. This combination can also be used to transform aldehydes into dibromoalkenes, which are useful precursors for the

Chemoenzymatic synthesis and biological evaluation of enantiomerically enriched 1-(β-hydroxypropyl)imidazolium- and triazolium-based ionic liquids

• Paweł Borowiecki,
• Małgorzata Milner-Krawczyk and
• Jan Plenkiewicz

Beilstein J. Org. Chem. 2013, 9, 516–525, doi:10.3762/bjoc.9.56

• -propylene oxide with imidazole or 1,2,4-triazole. Lipase-catalyzed transesterification of alcohols with vinyl acetate resulted in kinetic enantiomers resolution. Separated (S)-enantiomers of (+)-1-(1H-imidazol-1-yl)propan-2-ol and (+)-1-(1H-1,2,4-triazol-1-yl)propan-2-ol were quaternized with alkyl bromides

Copper-catalyzed CuAAC/intramolecular C–H arylation sequence: Synthesis of annulated 1,2,3-triazoles

• Rajkumar Jeyachandran,
• Harish Kumar Potukuchi and
• Lutz Ackermann

Beilstein J. Org. Chem. 2012, 8, 1771–1777, doi:10.3762/bjoc.8.202

• catalytic efficacy. Subsequently, we explored the extension of this approach to the development of a chemoselective three-component one-pot reaction. Thus, we found that alkyl bromides 2 could be directly employed as user-friendly substrates for the in situ formation of the corresponding organic azides

• mandatory. Indeed, our strategy turned out to be viable in a nonsequential manner by directly employing equimolar amounts of the three substrates. Hence, inexpensive CuI allowed the direct assembly of aryl iodides 1, alkyl bromides 2 and NaN3 with excellent chemo- and regioselectivities (Scheme 4). Thereby

• chromatography on silica gel (n-hexane/EtOAc). Copper-catalyzed step-economical C–H arylation-based cascade reaction. Copper-catalyzed sequential catalysis with alkyne 1a. Copper-catalyzed reaction sequence using alkyl bromides 2. General reaction conditions: 1 (1.00 mmol), 2 (1.00 mmol), NaN3 (1.05 mmol), CuI

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

• palladium-catalyzed, norbornene-mediated C2-alkylation reaction with a broad spectrum of alkyl bromides [21]. Over the past few years, our group and others have explored C–H bond functionalization reactions using cobalt complexes as inexpensive transition-metal catalysts [22], which often feature mild

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

• preparation of 1 is also presented herein). Ketone 1 was α-alkylated in high yields to various 2 via sodium hydride deprotonation and reaction of the resulting enolate with a variety of alkyl bromides or iodides. Alkyl derivatives 2 may be converted conventionally to the corresponding oximes 3. The Beckmann

• trioxaadamantylacetate 6 (Scheme 2) [15]. Alkylation of this compound was accomplished via initial deprotonation with lithium hexamethyldisilazide in THF at −78 °C [19]. The resulting enolate was reacted with various alkyl bromides or iodides, initially at −78 °C and then at room temperature over 6–8 h. The α-alkyl

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• (assuming that the reported value is measured relative to SHE, that would correspond to −0.38 V vs SCE) [13]. Tetrakis-dimethylaminoethene (TDAE, 5: E11/2 = −0.78 V; E21/2 = −0.61 V vs SCE in MeCN) is a stronger reducing agent and converts electron-deficient alkyl bromides to the corresponding anions [14

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

• Kirsti Parikka and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2009, 5, No. 22, doi:10.3762/bjoc.5.22

• ) and odd carbon chain ylids, but its use is limited because of the poor availability of odd carbon chain alkyl bromides [28]. The synthesis of hapten derivatives of alkylresorcinols 2, potential compounds in the development of immunochemical analysis techniques, has not been reported previously. Only