6973-66-6Relevant academic research and scientific papers
Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Solvent-Assisted Organophotoredox Activation
Ranjan, Prabhat,Pillitteri, Serena,Coppola, Guglielmo,Oliva, Monica,Van der Eycken, Erik V.,Sharma, Upendra K.
, p. 10862 - 10870 (2021/09/08)
Despite their prevalence in organic synthesis, the application of boronic acids (BAs) as alkyl radical precursors in visible-light-assisted photocatalyzed reactions has been limited by their high oxidation potential. This study demonstrates the prominent
Site-Specific Alkene Hydromethylation via Protonolysis of Titanacyclobutanes
Bartfield, Noah M.,Frederich, James H.,Law, James A.
supporting information, p. 14360 - 14364 (2021/05/27)
Methyl groups are ubiquitous in biologically active molecules. Thus, new tactics to introduce this alkyl fragment into polyfunctional structures are of significant interest. With this goal in mind, a direct method for the Markovnikov hydromethylation of alkenes is reported. This method exploits the degenerate metathesis reaction between the titanium methylidene unveiled from Cp2Ti(μ-Cl)(μ-CH2)AlMe2 (Tebbe's reagent) and unactivated alkenes. Protonolysis of the resulting titanacyclobutanes in situ effects hydromethylation in a chemo-, regio-, and site-selective manner. The broad utility of this method is demonstrated across a series of mono- and di-substituted alkenes containing pendant alcohols, ethers, amides, carbamates, and basic amines.
Enantioselective Alkylation of 2-Alkylpyridines Controlled by Organolithium Aggregation
Gladfelder, Joshua J.,Ghosh, Santanu,Podunavac, Ma?a,Cook, Andrew W.,Ma, Yun,Woltornist, Ryan A.,Keresztes, Ivan,Hayton, Trevor W.,Collum, David B.,Zakarian, Armen
supporting information, p. 15024 - 15028 (2019/10/22)
Direct enantioselective α-alkylation of 2-alkylpyridines provides access to chiral pyridines via an operationally simple protocol that obviates the need for prefunctionalization or preactivation of the substrate. The alkylation is accomplished using chiral lithium amides as noncovalent stereodirecting auxiliaries. Crystallographic and solution NMR studies provide insight into the structure of well-defined chiral aggregates in which a lithium amide reagent directs asymmetric alkylation.
Photocatalyzed Site-Selective C(sp3)-H Functionalization of Alkylpyridines at Non-Benzylic Positions
Fukuyama, Takahide,Nishikawa, Tomohiro,Yamada, Keiichi,Ravelli, Davide,Fagnoni, Maurizio,Ryu, Ilhyong
supporting information, p. 6436 - 6439 (2017/12/08)
Tetrabutylammonium decatungstate (TBADT)-photocatalyzed C-H functionalization of alkylpyridines was investigated. Unlike alkylbenzene counterparts, alkylation of α-C-H bonds did not proceed for the reaction of 2- and 4-alkylpyridines and reluctantly proceeded for 3-alkylpyridines, which allow site-selective C(sp3)-H functionalization at nonbenzylic positions. The observed nonbenzylic site selectivities are rationalized by the polar inductive effects of pyridyl groups in the SH2 transition states. Consecutive γ-functionalization and α-bromofunctionalization were successfully carried out in selected cases.
Zn-promoted regio- and sequence-selective one-pot joining reactions of three components: vinylpyridines, alkyl iodides, and carbonyl compounds (or nitriles)
Mineyama, Kenji,Maekawa, Hirofumi,Kohsaka, Akihiro,Yamamoto, Yoshimasa,Nishiguchi, Ikuzo
experimental part, p. 7706 - 7711 (2009/12/04)
Addition of alkyl iodides (3) into the solution containing 2-(or 4-)vinylpyridine (1 or 2) and carbonyl compounds (6) in the presence of Zn-powder (99.9%) in acetonitrile under refluxing brought about regio- and sequence-selective joining reaction of thre
Intramolecular Photochemical Hydrogen Abstraction in 2-Alkylpyrazines and 2-Alkylpyridines
Mukherjee, Ashis,Duggan, Sandhya A. M.,Agosta, William C.
, p. 178 - 181 (2007/10/02)
Photochemical hydrogen abstraction in 2-alkylpyrazines 5-8 and 2-alkylpyridines 9-11 proceeds analogously to the process of eq 1.Hydroxylic solvent causes quantum yields for pyrazine fragmentation products (Φp) to increase about 1 order of magnitude.Pyridine fragmentation takes place from both singlet and triplet states.Pyrazine fragmentations follow Stern-Volmer kinetics with modest bond strength selectivity (1 deg : 3 deg ca. 1:17 for 5a and 5c).Methyl substitution lowers the rate of abstraction in pyrazines and trifluoromethyl substitution increases Φp in pyridines.It is suggested that these effects reflect changes in the n?* and ??* character of the reactive excited states.
