220322-74-7Relevant academic research and scientific papers
Facile Direct Coupling Reactions of MOM-protected Benzylic Alcohols Using Aluminum Chloride
Bui, Tien Tan,Kim, Hee-Kwon
supporting information, p. 1195 - 1198 (2021/08/03)
MOM group is one of the most commonly used protecting groups for alcohols. This study describes novel direct functionalization of the MOM-protected benzylic alcohols. Preparation of allylic compounds from benzyl MOM ethers was successfully achieved by utilization of allyltrimethylsilane and AlCl3. In addition, direct azidation of benzyl MOM ethers using TMSN3 was successful carried out under AlCl3-mediated reaction conditions. These results demonstrate that this novel synthetic procedure is a promising approach to direct functionalization of MOM-protected alcohols including allylation and azidation.
In Situ Generated Gold Nanoparticles on Active Carbon as Reusable Highly Efficient Catalysts for a Csp3 ?Csp3 Stille Coupling
Holz, Julia,Pfeffer, Camilla,Zuo, Hualiang,Beierlein, Dennis,Richter, Gunther,Klemm, Elias,Peters, René
, p. 10330 - 10334 (2019/06/27)
Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional Csp2-Csp2 cross-coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form Csp3-Csp3 bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross-coupling reaction of an organic halide and an organometallic reagent.
Scandium as a pre-catalyst for the deoxygenative allylation of benzylic alcohols
?oli?, Ivan,Seankongsuk, Pattarakiat,Loh, Joanna Kejun,Vilaivan, Tirayut,Bates, Roderick W.
supporting information, p. 119 - 123 (2017/12/27)
Scandium triflate is an effective pre-catalyst for the deoxygenative allylation of benzylic alcohols with a narrow substrate window. The reaction is shown to proceed through a "hidden Br?nsted acid" mechanism. The reaction is efficient provided that the aryl group is neither too electron rich nor too electron poor. It is shown that this allows useful selectivity. The reaction also works for benzyhydryl alcohols with broader scope. The reaction may also be catalysed by Nafion.
A general Br?nsted acid-catalyzed allylation of benzhydryl alcohols
Orizu, Ifedi,Bolshan, Yuri
supporting information, p. 5798 - 5800 (2016/12/03)
Efficient Br?nsted acid-catalyzed allylation of benzhydryl alcohols has been developed. The reaction occurs within 5?min in the presence of sub-stoichiometric amounts of HBF4·OEt2to afford the desired products in good to excellent yields. A variety of functional groups were tolerated under the developed conditions including amides, aldehydes, hydroxyl and carboxylic acid.
Nickel-catalyzed allylic alkylation with diarylmethane pronucleophiles: Reaction development and mechanistic insights
Sha, Sheng-Chun,Jiang, Hui,Mao, Jianyou,Bellomo, Ana,Jeong, Soo A.,Walsh, Patrick J.
supporting information, p. 1070 - 1074 (2016/01/20)
Palladium-catalyzed allylic substitution reactions are among the most efficient methods to construct C-C bonds between sp3-hybridized carbon atoms. In contrast, much less work has been done with nickel catalysts, perhaps because of the different mechanisms of the allylic substitution reactions. Palladium catalysts generally undergo substitution by a "soft"-nucleophile pathway, wherein the nucleophile attacks the allyl group externally. Nickel catalysts are usually paired with "hard" nucleophiles, which attack the metal before C-C bond formation. Introduced herein is a rare nickel-based catalyst which promotes substitution with diarylmethane pronucleophiles by the soft-nucleophile pathway. Preliminary studies on the asymmetric allylic alkylation are promising. Just a softy: Contrary to what would be predicted, organosodium nucleophiles derived from diarylmethane pronucleophiles are shown to behave as soft nucleophiles in nickel-catalyzed allylic substitution reactions. This general reaction is demonstrated to proceed through a double inversion pathway. A promising asymmetric version is presented.
Raising the p K a Limit of soft nucleophiles in palladium-catalyzed allylic substitutions: Application of diarylmethane pronucleophiles
Sha, Sheng-Chun,Zhang, Jiadi,Carroll, Patrick J.,Walsh, Patrick J.
supporting information, p. 17602 - 17609 (2014/01/06)
The Tsuji-Trost allylic substitution reaction provides a useful and efficient approach to construct C-C bonds between sp3-hybridized carbons. The widely accepted paradigm for classifying the mode of attack of nucleophiles on palladium π-allyl intermediates in the Tsuji-Trost reaction is based on the pKa of the pronucleophile: (1) stabilized or soft carbon nucleophiles and heteroatom nucleophiles (e.g., pronucleophiles with pKa's a's > 25). One of the keys to the continuing development of allylic substitution processes remains broadening the scope of soft nucleophiles. Herein we report a general method for the room temperature Pd-catalyzed allylic substitution with diarylmethane derivatives (pKa's up to 32). The synthetic significance of the method is that it provides a rapid access to products containing allylated diarylmethyl motifs. The method is general for a wide range of nucleophiles derived from diarylmethanes and heterocyclic derivatives. A procedure for the Pd-catalyzed allylic substitutions to afford diallylation products with quaternary centers is also described. With triarylmethanes and alkylated diarylmethanes the corresponding allylated products are isolated. We anticipate that the described method will be a valuable complement to the existing arsenal of nucleophiles in Pd-catalyzed allylic substitutions. Mechanistic studies show that the nucleophile derived from diphenylmethane undergoes external attack on π-allyl palladium species under our reaction conditions. This unexpected observation indicates that diarylmethane derivatives behave as soft or stabilized nucleophiles. The results of this study indicate that the cutoff between soft and hard nucleophiles should be raised from a pronucleophile pK a of 25 to at least 32.
Direct allylation of α-aryl alcohols with allyltrimethylsilane catalyzed by heterogeneous tin ion-exchanged montmorillonite
Wang, Jiacheng,Masui, Yoichi,Onaka, Makoto
experimental part, p. 3300 - 3303 (2010/07/06)
The direct allylation of α-aryl alcohols with allyltrimethylsilane efficiently proceeded in the presence of tin ion-exchanged montmorillonite under mild conditions according to the proper addition order of reactants and a catalyst.
Generation of diarylcarbenium ion poolsviaelectrochemical C-H bond dissociation
Okajima, Masayuki,Soga, Kazuya,Watanabe, Takashi,Terao, Kimitada,Nokami, Toshiki,Suga, Seiji,Yoshida, Jun-Ichi
experimental part, p. 594 - 599 (2009/11/30)
The "cation pools" of diarylcarbenium ions have been generated by the low-temperature electrochemical oxidation of diphenylmethane derivatives. In addition to diphenylmethanes having various substituents, 9,10-dihydroanthracene, dibenzosuberane, and xanth
Nucleophilic substitution reactions of alcohols with use of montmorillonite catalysts as solid Bronsted acids
Motokura, Ken,Nakagiri, Nobuaki,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 6006 - 6015 (2008/02/10)
(Chemical Equation Presented) We have developed an environmentally benign synthetic approach to nucleophilic substitution reactions of alcohols that minimizes or eliminates the formation of byproducts, resulting in a highly atom-efficient chemical process. Proton- and metal-exchanged montmorillonites (H- and Mn+-mont) were prepared easily by treating Na +-mont with an aqueous solution of hydrogen chloride or metal salt, respectively. The H-mont possessed outstanding catalytic activity for nucleophilic substitution reactions of a variety of alcohols with anilines, because the unique acidity of the H-mont catalyst effectively prevents the neutralization by the basic anilines. In addition, amides, indoles, 1,3-dicarbonyl compounds, and allylsilane act as nucleophiles for the H-mont-catalyzed substitutions of alcohols, which allowed efficient formation of various C-N and C-C bonds. The solid H-mont was reusable without any appreciable loss in its catalytic activity and selectivity. Especially, an Al3+-mont showed high catalytic activity for the α-benzylation of 1,3-dicarbonyl compounds with primary alcohols due to cooperative catalysis between a protonic acid site and a Lewis acidic Al3+ species in its interlayer spaces.
Oxidative generation of diarylcarbenium ion pools
Okajima, Masayuki,Soga, Kazuya,Nokami, Toshiki,Suga, Seiji,Yoshida, Jun-Ichi
, p. 5005 - 5007 (2007/10/03)
(Figure Presented) "Cation pools" of diarylcarbenium ions have been generated by the oxidative C-H bond dissociation of diarylmethanes using anodic oxidation. "Diarylcarbenium ion pools" thus generated react with various nucleophiles, such as allylsilanes
