14559-88-7Relevant academic research and scientific papers
Rate dependence on inductive and resonance effects for the organocatalyzed enantioselective conjugate addition of alkenyl and alkynyl boronic acids to β-indolyl enones and β-pyrrolyl enones
Boylan, Amy,Li, Jian-Yuan,Lundy, Brian J.,May, Jeremy A.,Nguyen, Thien S.,Sundstrom, Sasha,Vallakati, Ravikrishna
, (2021/06/16)
Two key factors bear on reaction rates for the conjugate addition of alkenyl boronic acids to heteroaryl-appended enones: the proximity of inductively electron-withdrawing heteroatoms to the site of bond formation and the resonance contribution of available heteroatom lone pairs to stabilize the developing positive charge at the enone β-position. For the former, the closer the heteroatom is to the enone β-carbon, the faster the reaction. For the latter, greater resonance stabilization of the benzylic cationic charge accelerates the reaction. Thus, reaction rates are increased by the closer proximity of inductive electron-withdrawing elements, but if resonance effects are involved, then increased rates are observed with electron-donating ability. Evidence for these trends in isomeric substrates is presented, and the application of these insights has allowed for reaction conditions that provide improved reactivity with previously problematic substrates.
Preparation of 2,2-dimethyl-vinyl boric acid method
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Paragraph 0025, (2017/01/12)
The invention belongs to the technical field of chemical industry, and in particular discloses a method for preparing 2,2-dimethyl vinyl boric acid. The method is characterized by comprising the steps of enabling an organic solvent 1 and 3,3-dimethyl acrylic acid to react with bromine for 3-4 hours at 10-60 DEG C, adjusting the pH value to 9-10 by using alkali after reaction, reacting for 2-3 hours at 30-60 DEG C, standing for layering after reaction, and distilling an organic layer to obtain 2,2-dimethyl vinyl bromine; enabling an organic solvent 2 to react with 2,2-dimethyl vinyl bromine for 2-3 hours at minus 78 to minus 40 DEG C under the action of lithium and a boronizing agent, adjusting the pH value to 3-4 by using hydrochloric acid, performing extraction by using acetic ether, concentrating an organic layer, pulping and filtering through a non-polar hydrocarbon solvent, and drying to obtain 2,2-dimethyl vinyl boric acid. The method disclosed by the invention has the characteristics of safety, environment friendliness and easiness in operation, and is suitable for industrial production.
A general method for the enantioselective synthesis of α-chiral heterocycles
Le, Phong Q.,Nguyen, Thien S.,May, Jeremy A.
supporting information, p. 6104 - 6107 (2013/02/23)
The enantioselective formation of stereocenters proximal to unprotected heterocycles has been accomplished. Thus, vinyl boronic acids are added to heterocycle-appended enones via a modified-BINOL catalyst. Catalyst design was key to enable a general reaction. High yields and useful er's are observed for a host of common heteroaryls.
Enantioselective conjugate addition of alkenylboronic acids to indole-appended enones
Lundy, Brian J.,Jansone-Popova, Santa,May, Jeremy A.
supporting information; experimental part, p. 4958 - 4961 (2011/11/29)
An enantioselective addition of alkenylboronic acids and alkynylboronic esters to unprotected indole-appended enones is reported. This transformation proceeds with high enantioselectivity and high product yields via the use of catalytic amounts of 3,3′-bis(pentafluorophenyl)-BINOL and Mg(Ot-Bu) 2. A range of α-branched indole derivatives are available from the transformation.
Pinene-derived iminodiacetic acid (PIDA): A powerful ligand for stereoselective synthesis and iterative cross-coupling of C(sp3) boronate building blocks
Li, Junqi,Burke, Martin D.
supporting information; experimental part, p. 13774 - 13777 (2011/10/09)
Efficient access to chiral C(sp3) boronates in stereochemically pure form is critical for realizing the substantial potential of such building blocks in complex-molecule synthesis. We herein report that a pinene-derived iminodiacetic acid (PIDA) ligand enables the highly diastereoselective synthesis of a wide range of oxiranyl C(sp3) boronates from the corresponding olefins. These oxiranyl PIDA boronates, in turn, can be readily transformed into unprecedented stable α-boryl aldehydes via a novel 1,2-migration of the boronate group that proceeds with complete maintenance of stereochemical purity. B-Protected haloboronic acids containing dual sp3-hybridized C centers are readily accessible via this platform, and the herein demonstrated capacity for stereocontrolled iterative C(sp3) cross-coupling with this novel type of bifunctional reagent to access a medicinally important chiral small-molecule target in highly enantioenriched form represents a substantial advance for the building-block-based approach to synthesis.
Asymmetric Rh(I)-catalyzed addition of MIDA boronates to N-Tert -butanesulfinyl aldimines: Development and comparison to trifluoroborates
Brak, Katrien,Ellman, Jonathan A.
supporting information; experimental part, p. 3147 - 3150 (2010/07/09)
The Rh(I)-catalyzed addition of alkenyl and aryl MIDA boronates to N-tert-butanesulfinyl aromatic and aliphatic imines proceeds in good yields (up to 99%) and with very high selectivity (98:2 to >99:1). In comparison to trifluoroborates, higher yields and
Total synthesis of (-)-aurantioclavine
Brak, Katrien,Ellman, Jonathan A.
supporting information; experimental part, p. 2004 - 2007 (2010/07/06)
Figure presented The concise total synthesis of (-)-aurantioclavine has been achieved by taking advantage of strategies for the asymmetric alkenylation of N-tert-butanesulfinyl imines. The enantiomerically pure natural product was prepared in 6 steps and 27% overall yield by using Rh-catalyzed addition of a N-methyliminodiacetic acid (MIDA) boronate and in 5 steps and 29% yield by employing a Grignard reagent addition sequence.
Lithium bis(ethylenedioxyboryl)methide and its reactions with carbonyl compounds and with the chlorotriphenyl derivatives of germanium, tin and lead
Matteson, Donald S.,Jesthi, Pradipta K.
, p. 25 - 37 (2007/10/05)
Transesterification of tris(dimethoxyboryl)methane, HC[B(OCH3)2]3, with ethylene glycol yielded tris(ethylenedioxyboryl)methane (I), HC(BO2C2H4)3 which with methyllithium in THF at -70°C precipitated lithium bis(ethylenedioxyboryl)methide (II), Li+ HC(BO2C2H4)2-. Reaction of II with Ph3MCl, where M = Ge, Sn, or Pb, gave Ph3MCH(BO2C2H4)2. The analogous 1,3-propanediol ester, Li+HC(BO2C3H6)2-, yielded Ph3MCH(BO2C3H6)2. Treatment of Ph3SnCH(BO2C2H4)2 with MeLi followed by Ph3SnCl gave (Ph3Sn)2CHBO2C2H4, showing that one B and one Sn atom are sufficient to stabilize a carbanion. Reaction of II with aldehydes gave high yields of 1-alkene-1-boronic esters, RCHCHBO2C2H4, with unexpectedly high stereoselectivity, 90-100% trans by NMR analysis. Aqueous work-up of these boronic esters yielded the boronic acids, RCHCHB (OH)2, which crystallized as the pure trans isomers. Ketones react with II in an analogous manner. The reaction with acetophenone was not stereospecific. Functional group compatibility has been demonstrated in condensations of II with 1,3-dichloroacetone, cinnamaldehyde, p-nitrobenzaldehyde, and p-dimethylaminobenzaldehyde. The trans geometry of the major isomer of CH3CHCHBO2C2H4 was proved by B-butylation with butyllithium followed by rearrangement with iodine and base to form cis-2-heptene, a sequence of known stereochemistry, and analogous structure proofs were carried out with cis-CH3CHCHBO2C2H4 and trans-C6H5CHCHBO2C2H4.
