497-36-9Relevant articles and documents
A solution of borane in tetrahydrofuran. A stereoselective reducing agent for reduction of cyclic ketones to thermodynamically more stable alcohols
Cha,Moon,Park
, p. 7514 - 7515 (2001)
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276. Hydroboration and Oxymercuration of Some 1-Substituted Norborn-2-enes
Luef, Wolfgang,Voegeli, Ulrich-Christian,Keese, Reinhart
, p. 2729 - 2739 (1983)
The 1-substituted norborn-2-enes 11-13 and 18 react with electrophiles under kinetic control preferentially in 2-position.The regioselectivity in oxymercuration is higher than in hydroboration and reaction with aqueous palladium chloride.
Decomposition of endo- and exo-(2-Norbornyl)formyl m-Chlorobenzoyl Peroxides
Walling, Cheves,Humphreys, Robert R. W.,Sloan, John P.,Miller, Traci
, p. 5261 - 5263 (1981)
The subject peroxides undergo first-order decomposition in several solvents with rates increasing moderately with solvent polarity and endo/exo rates in a ratio of 1:10-100.Carboxyl inversion product, ROCOOCOAr, and other "polar" products are formed with no evidence for significant free-radical production.Products from an exo-peroxide have exclusively exo configurations, but carboxyl inversion product from endo peroxide contains small amounts of exo isomer.In acetic acid, 2-norbornyl acetate is a major product, with endo/exo ratio of 14:86 from the endo-peroxide.Optically active exo-peroxide in acetic acid gives exo-2-norbornyl acetate with 6percent net retention of configuration.The results are discussed in terms of successive ion pairs and carboxyl inversion product arising early on the reaction path and other products later.
Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
supporting information, p. 103 - 108 (2021/01/13)
Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
, p. 13659 - 13667 (2020/11/30)
Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
