More Like this

1. Stereoselective syntheses of 2-methyl-1,3-diol acetals via Re-catalyzed [1,3]-allylic alcohol transposition

   https://doi.org/10.1039/d2sc07059f  

   Liu, Jiaming; Chen, Ming (August 2023, Chemical Science)

   Rhenium-catalyzed stereoselective transposition of allylic alcohols is reported. In the presence of 1 mol% of Re 2 O 7 , ( E )- or ( Z )-δ-hydroxymethyl- anti -homoallylic alcohols were converted into the acetals of 2-methyl-1,3- syn -diols with excellent diastereoselectivities. 1,3- syn -Diol acetals can also be synthesized from ( E )-δ-hydroxymethyl- syn -homoallylic alcohols. 

   more » « less
2. Catalytic asymmetric transformations of racemic α-borylmethyl-( E )-crotylboronate via kinetic resolution or enantioconvergent reaction pathways

   https://doi.org/10.1039/d1sc04047b  

   Gao, Shang; Liu, Jiaming; Chen, Ming (October 2021, Chemical Science)

   We report herein catalytic asymmetric transformations of racemic α-borylmethyl-( E )-crotylboronate. The Brønsted acid-catalyzed kinetic resolution–allylboration reaction sequence of the racemic reagent gave ( Z )-δ-hydroxymethyl- anti -homoallylic alcohols with high Z -selectivities and enantioselectivities upon oxidative workup. In parallel, enantioconvergent pathways were utilized to synthesize chiral nonracemic 1,5-diols and α,β-unsaturated aldehydes with excellent optical purity. 

   more » « less
3. Diastereoconvergent synthesis of anti -1,2-amino alcohols with N-containing quaternary stereocenters via selenium-catalyzed intermolecular C–H amination

   https://doi.org/10.1039/d2sc02648a  

   Zheng, Tianyi; Berman, Janna L.; Michael, Forrest E. (August 2022, Chemical Science)

   We report a diastereoconvergent synthesis of anti -1,2-amino alcohols bearing N-containing quaternary stereocenters using an intermolecular direct C–H amination of homoallylic alcohol derivatives catalyzed by a phosphine selenide. Destruction of the allylic stereocenter during the selenium-catalyzed process allows selective formation of a single diastereomer of the product starting from any diastereomeric mixture of the starting homoallylic alcohol derivatives, eliminating the need for the often-challenging diastereoselective preparation of starting materials. Mechanistic studies show that the diastereoselectivity is controlled by a stereoelectronic effect (inside alkoxy effect) on the transition state of the final [2,3]-sigmatropic rearrangement, leading to the observed anti selectivity. The power of this protocol is further demonstrated on an extension to the synthesis of syn -1,4-amino alcohols from allylic alcohol derivatives, constituting a rare example of 1,4-stereoinduction. 

   more » « less
4. Stereochemical Control via Chirality Pairing: Stereodivergent Syntheses of Enantioenriched Homoallylic Alcohols

   https://doi.org/10.1002/anie.202107004  

   Gao, Shang; Duan, Meng; Liu, Jiaming; Yu, Peiyuan; Houk, Kendall N.; Chen, Ming (October 2021, Angewandte Chemie International Edition)

   Abstract We report herein the development of stereodivergent syntheses of enantioenriched homoallylic alcohols using chiral nonracemic α‐CH₂Bpin‐substituted crotylboronate. Chiral phosphoric acid (S)‐A‐catalyzed asymmetric allyl addition with the reagent gaveZ‐anti‐homoallylic alcohols with excellent enantioselectivities andZ‐selectivities. When the enantiomeric acid catalyst (R)‐Awas utilized, the stereoselectivity was completely reversed andE‐anti‐homoallylic alcohols were obtained with highE‐selectivities and excellent enantioselectivities. By pairing the chirality of the boron reagent with the catalyst, two complementary stereoisomers of chiral homoallylic alcohols can be obtained selectively from the same boron reagent. DFT computational studies were conducted to probe the origins of the observed stereoselectivity. These reactions generate highly enantioenriched homoallylic alcohol products that are valuable for rapid construction of polyketide structural frameworks. 

   more » « less
5. Stereospecific and Regioselective Synthesis of E -Allylic Alcohols through Reductive Cross Coupling of Terminal Alkynes

   https://doi.org/10.1021/jacs.3c06963  

   Shaff, Austin B; Yang, Langxuan; Lee, Mitchell T; Lalic, Gojko (November 2023, Journal of the American Chemical Society)

   We have developed a convergent method for the synthesis of allylic alcohols that involves a reductive coupling of terminal alkynes with α-chloro boronic esters. The new method affords allylic alcohols with excellent regioselectivity (anti-Markovnikov) and an E/Z ratio greater than 200:1. The reaction can be performed in the presence of a wide range of functional groups and has a substrate scope that complements the stoichiometric alkenylation of α-chloro boronic esters performed using alkenyl lithium and Grignard reagents. The transformation is stereospecific and allows for the robust and highly selective synthesis of chiral allylic alcohols. Our studies support a mechanism that involves hydrocupration of the alkyne and cross-coupling of the alkenyl copper intermediate with α-chloro boronic esters. Experimental evidence excludes a radical mechanism of the cross-coupling step and is consistent with the formation of a boron-ate intermediate and a 1,2-metalate shift. 

   more » « less