We report herein a rare example of enantiodivergent aldehyde addition with β‐alkenyl allylic boronates via chiral Brønsted acid catalysis. 2,6‐Di‐9‐anthracenyl‐substituted chiral phosphoric acid‐catalyzed asymmetric allylation using β‐vinyl substituted allylic boronate gave alcohols with
We report herein a rare example of enantiodivergent aldehyde addition with β‐alkenyl allylic boronates via chiral Brønsted acid catalysis. 2,6‐Di‐9‐anthracenyl‐substituted chiral phosphoric acid‐catalyzed asymmetric allylation using β‐vinyl substituted allylic boronate gave alcohols with
- NSF-PAR ID:
- 10373663
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 61
- Issue:
- 41
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract R absolute configuration. The sense of asymmetric induction of the catalyst in these reactions is opposite to those in prior reports. Moreover, in the presence of the same acid catalyst, the reactions with β‐2‐propenyl substituted allylic boronate generated homoallylic alcohol products withS absolute configuration. Unusual substrate‐catalyst C−H⋅⋅⋅π interactions in the favoured reaction transition state were identified as the origins of observed enantiodivergence through DFT computational studies. -
Abstract Allylboron reagents are popular in synthesis owing to their versatility and the predictable stereochemical outcomes of their reactions with carbonyl compounds. Herein, we describe the synthesis of (
Z ,Z )‐hexadienyl bis‐boronate1 , a configurationally stable, crystalline, and easy to handle compound, which represents a class of bis‐allylic boron reagents with heretofore untapped synthetic potential. In combination with a chiral phosphoric acid catalyst, the reagent can be employed for the enantioselective allyl transfer reaction to a variety of one‐pot transformations, enabling swift access to functionalized 1,n ‐diols. The in situ conversion of the reagent into the corresponding bis‐borinic ester allows for the direct and diastereoselective two‐fold allyl transfer to aldehydes. This affordsC 2‐ orCi ‐symmetric stereotetrads containing a 1,4‐diol moiety for natural product synthesis. The usefulness of our method was demonstrated with a short synthesis of the lignan (±)‐neo‐olivil. -
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 )‐A was 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. -
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 )‐A was 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. -
Abstract The traceless Petasis borono‐Mannich reaction of enals, sulfonylhydrazines, and allylboronates, catalyzed by chiral biphenols, results in an asymmetric reductive transposition of the in situ generated allylic diazene. Acyclic 1,4‐diene products bearing either alkyl‐ or aryl‐substituted benzylic stereocenters are afforded in excellent yields and enantiomeric ratios of up to 99:1. The use of crotylboronates in the reaction results in concomitant formation of two stereocenters in either a 1,4‐
syn oranti relationship from the correspondingE ‐ orZ ‐crotylboronate used in the reaction. The use of β‐monosubstituted enals in the asymmetric traceless Petasis borono‐Mannich reaction of crotylboronates installs tertiary methyl‐bearing stereocenters in good yields and high enantioselectivities.