121883-32-7Relevant academic research and scientific papers
Pseudo-macrocyclic chelation control in remote asymmetric induction. Highly efficient 1,7-asymmetric inductive hydride reduction and Grignard reaction of γ-keto esters of 1,1′-binaphthalen-2-ols bearing an appropriate oligoether group as the 2′-substituent
Tamai, Yasufumi,Hattori, Tetsutaro,Date, Masamitsu,Koike, Shinji,Kamikubo, Yoshinori,Akiyama, Masahiro,Seino, Kazuhiro,Takayama, Hideki,Oyama, Tomohito,Miyano, Sotaro
, p. 1685 - 1694 (2007/10/03)
Highly efficient 1,7-asymmetric induction was achieved in DIBAL-H reduction and Grignard reaction of γ-keto esters of podand-type 1,1′-binaphthalen-2-ol derivatives bearing an appropriate oligoether group as the 2′-substituent. Thus, the DIBAL-H reduction of keto esters 4 in dichloromethane-toluene at -78°C in the presence of an excess of MgBr2·OEt2 afforded, after further, reduction of the resulting diastereomeric hydroxy esters, 1,4-diol 8 with up to 92% optical yield. A similar treatment of keto esters 4, 5 and 7 with Grignard reagents gave the corresponding 4,4-disubstituted butan-4-olides 10-13 with up to 99% optical yield. The complexation experiments of keto ester 4b suggested that the highly efficient 1,7-asymmetric induction originated from the formation of a pseudo-macrocyclic magnesium complex composed of the podand keto ester and MgBr2.
Mild and practical acylation of alcohols with esters or acetic anhydride under distannoxane catalysis
Orita, Akihiro,Sakamoto, Katsumasa,Hamada, Yuji,Mitsutome, Akihiro,Otera, Junzo
, p. 2899 - 2910 (2007/10/03)
Distannoxane catalysts effect acylation of alcohols by action of esters and acetic anhydride. In particular, use of enol esters provides an extremely useful method. Primary alcohols are acylated in preference to secondary ones as well as phenol. Both acid- and base-sensitive functional groups remain intact. Especially unique is the discrimination of thio function which is completely tolerant under the present reaction conditions. This method is highly practical since operation is quite simple. Esters and solvents can be used without purification and no inert atmosphere is necessary. The products can be isolated simply by column chromatography or distillation without aqueous workup.
Preparation of Functionalized Dialkylzinc Reagents via an Iodine-Zinc Exchange Reaction. Highly Enantioselective Synthesis of Functionalized Secondary Alcohols
Rozema, Michael J.,AchyuthaRao, Sidduri,Knochel, Paul
, p. 1956 - 1958 (2007/10/02)
Functionalized dialkylzincs are obtained by the reaction of polyfunctional alkyl iodides with Et2Zn in excellent yield.Their treatment with aldehydes, in the presence of the titanium catalyst 6, affords functionalized secondary alcohols with high enantios
Cobalt(II) Chloride Catalyzed Acylation of Alcohols with Acetic Anhydride: Scope and Mechanism
Iqbal, Javed,Srivastava, Rajiv Ranjan
, p. 2001 - 2007 (2007/10/02)
Cobalt(II) chloride catalyzes the acetylation of a variety of alcohols with acetic anhydride in excellent yield.Primary hydroxyl groups can be selectively acylated in the presence of secondary and tertiary ones while the secondary hydroxyl groups can be preferentially acetylated in the presence of tertiary ones.Tertiary alcohols have been found to give ketones, acetoacetates, olefins, and diketene in addition to the acetate.The β-hydroxy esters and ketones can be acylated under these conditions without any elimination, and this reaction has been compared with 4-(dimethylamino)pyridine (DMAP)-mediated acylations where elimination of the resulting β-acetoxy carbonyl compound is observed.A detailed investigation of the acylation of tertiary alcohols has revealed that these reactions proceed via a tertiary alkoxy radical and ketene.A mechanism for these acylations is proposed by invoking an electron-transfer process.
