69611-02-5Relevant articles and documents
Diastereoselective Addition of Prochiral Nucleophilic Alkenes to α-Chiral N-Sulfonyl Imines
Ando, Kaori,Fettinger, James,Gutierrez, David A.,Houk, K. N.,Shaw, Jared T.
supporting information, p. 1164 - 1168 (2022/02/14)
The Lewis-acid-promoted addition of prochiral E- and Z-allyl nucleophiles to chiral α-alkoxy N-tosyl imines is described. Alkene geometry is selectively transferred to the newly formed carbon-carbon bond, resulting in stereochemical control of C1, C2, and C3 of the resulting 2-alkoxy-3-N-tosyl-4-alkyl-5-hexene products. A computational analysis to elucidate the high selectivity is also presented. This methodology was employed in the synthesis of two naturally occurring isomers of clausenamide.
Selecting double bond positions with a single cation-responsive iridium olefin isomerization catalyst
Camp, Andrew M.,Kita, Matthew R.,Blackburn, P. Thomas,Dodge, Henry M.,Chen, Chun-Hsing,Miller, Alexander J.M.
, p. 2792 - 2800 (2021/03/01)
The catalytic transposition of double bonds holds promise as an ideal route to alkenes of value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, normally requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst selectively produces either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on noncovalent modifications.
Nickel-Catalysed Allylboration of Aldehydes
Dennis, Francesca M.,Partridge, Benjamin M.,Robertson, Craig C.
, p. 1903 - 1914 (2020/07/04)
A nickel catalyst for the allylboration of aldehydes is reported, facilitating the preparation of homoallylic alcohols in high diastereoselectivity. The observed diastereoselectivities and NMR experiments suggest that allylation occurs through a well-defined six-membered transition state, with nickel acting as a Lewis acid.
Guanidine–Copper Complex Catalyzed Allylic Borylation for the Enantioconvergent Synthesis of Tertiary Cyclic Allylboronates
Ge, Yicen,Cui, Xi-Yang,Tan, Siu Min,Jiang, Huan,Ren, Jingyun,Lee, Nicholas,Lee, Richmond,Tan, Choon-Hong
supporting information, p. 2382 - 2386 (2019/02/01)
An enantioconvergent synthesis of chiral cyclic allylboronates from racemic allylic bromides was achieved by using a guanidine–copper catalyst. The allylboronates were obtained with high γ/α regioselectivities (up to 99:1) and enantioselectivities (up to 99 % ee), and could be further transformed into diverse functionalized allylic compounds without erosion of optical purity. Experimental and DFT mechanistic studies support an SN2′ borylation process catalyzed by a monodentate guanidine–copper(I) complex that proceeds through a special direct enantioconvergent transformation mechanism.
Selective Isomerization of Terminal Alkenes to (Z)-2-Alkenes Catalyzed by an Air-Stable Molybdenum(0) Complex
Becica, Joseph,Glaze, Owen D.,Wozniak, Derek I.,Dobereiner, Graham E.
, p. 482 - 490 (2018/02/17)
Positional and stereochemical selectivity in the isomerization of terminal alkenes to internal alkenes is observed using the cis-Mo(CO)4(PPh3)2 precatalyst. A p-toluenesulfonic acid (TsOH) cocatalyst is essential for catalyst activity. Various functionalized terminal alkenes have been converted to the corresponding 2-alkenes, generally favoring the Z isomer with selectivity as high as 8:1 Z:E at high conversion. Interrogation of the catalyst initiation mechanism by 31P NMR reveals that cis-Mo(CO)4(PPh3)2 reacts with TsOH at elevated temperatures to yield a phosphine-ligated Mo hydride (MoH) species. Catalysis may proceed via 2,1-insertion of a terminal alkene into a MoH group and stereoselective β-hydride elimination to yield the (Z)-2-alkene.
Synthesis and biological activity evaluation of dolastatin 10 analogues with N-terminal modifications
Wang, Xin,Dong, Suzhen,Feng, Dengke,Chen, Yazhou,Ma, Mingliang,Hu, Wenhao
supporting information, p. 2255 - 2266 (2017/03/24)
We have described the synthesis of the two complex units (2R,3R,4S)-dolaproine (Dap) and (3R,4S,5S)-dolaisoleuine (Dil) of dolastatin 10 from natural amino acids. The stereoselective syntheses of N-Boc-Dap (4a) and N-Boc-(2S)-iso-Dap (4b) were performed by employing crotylation of N-Boc-L-prolinal as a key step. Barbier-type allylation of N-Boc-L-isoleucinal provided a mild and convenient approach for the synthesis of N-Boc-Dil (5a) and N-Boc-(3S)-iso-Dil (5b). Ten dolastatin 10 analogues have been designed and synthesized with N-terminal modifications based on the known compound monomethylauristatin F (MMAF, 3). In comparison with MMAF (3), four of the compounds showed enhanced potency against HCT 116 human colon cancer cells in?vitro.
An alternative mechanism for the cobalt-catalyzed isomerization of terminal alkenes to (Z)-2-alkenes
Schmidt, Anastasia,N??dling, Alexander R.,Hilt, Gerhard
supporting information, p. 801 - 804 (2015/03/04)
The cobalt-catalyzed selective isomerization of terminal alkenes to the thermodynamically less-stable (Z)-2-alkenes at ambient temperatures takes place by a new mechanism involving the transfer of a hydrogen atom from a Ph2PH ligand to the starting material and the formation of a phosphenium complex, which recycles the Ph2PH complex through a 1,2-H shift.
Enantioselective synthesis of anti homoallylic alcohols from terminal alkynes and aldehydes based on concomitant use of a cationic iridium complex and a chiral phosphoric acid
Miura, Tomoya,Nishida, Yui,Morimoto, Masao,Murakami, Masahiro
, p. 11497 - 11500 (2013/09/02)
We report a highly diastereo- and enantioselective synthesis of anti homoallylic alcohols from terminal alkynes via (E)-1-alkenylboronates based upon two catalytic reactions: a cationic iridium complex-catalyzed olefin transposition of (E)-1-alkenylboronates and a chiral phosphoric acid-catalyzed allylation reaction of aldehydes.
SYNTHESIS OF BORONIC ESTERS AND BORONIC ACIDS USING GRIGNARD REAGENTS
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Paragraph 0088, (2013/03/26)
Boronic esters and boronic acids are synthesized at ambient temperature in an ethereal solvent by the reaction of Grignard reagents with a boron-containing substrate. The boron-containing substrate may be a boronic ester such as pinacolborane, neopentylglycolborane, or a dialkylaminoborane compound such as diisopropylaminoborane. The Grignard reagents may be preformed or generated from an alkyl, alkenyl, aryl, arylalkyl, heteroaryl, vinyl, or allyl halide compound and Mg°. When the boron-containing substrate is a boronic ester, the reactions generally proceed at room temperature without added base in about 1 to 3 hours to form a boronic ester compound. When the boron-containing substrate is a dialkylaminoborane compound, the reactions generally proceed to completion at 0°C in about 1 hour to form a boronic acid compound.
Ni- and pd-catalyzed synthesis of substituted and functionalized allylic boronates
Zhang, Ping,Roundtree, Ian A.,Morken, James P.
supporting information; experimental part, p. 1416 - 1419 (2012/06/01)
Two highly efficient and convenient methods for the synthesis of functionalized and substituted allylic boronates are described. In one procedure, readily available allylic acetates are converted to allylic boronates catalyzed by Ni/PCy3 or Ni/PPh3 complexes with high levels of stereoselectivity and in good yields. Alternatively, the borylation can be accomplished with commercially available Pd catalysts [e.g., Pd 2(dba)3, PdCl2, Pd/C], starting with easily accessed allylic halides.
