Catalytic asymmetric 1,4-addition and [3 + 2] cycloaddition reactions using chiral calcium species prepared from isopropoxide bisoxazoline ligands have been developed. Glycine Schiff bases reacted with acrylic esters to afford products, glutamic acid derivatives, in high yields enantioselectivities. During the investigation of reactions, we unexpectedly found that a occurred crotonate affording substituted pyrrolidine derivatives On basis this finding, investigated cycloadditions, it was...

The direct, Ir-catalyzed, regio- and enantioselective amination of allylic alcohols with Lewis acid activators to form branched amine products is reported. reactions arylamines, benzylic amines, secondary aliphatic amines in the presence Nb(OEt)5 as activator occurred high regioselectivities enantioselectivities. These results led development Ir-catalyzed alcohol arylamines BPh3 catalytic amounts. are rare examples substitutions alcohols. They particularly unusual substitution generate from...

The group 2 alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) are among the most common elements on Earth, abundant in both sea Earth’s crust. Although they familiar our daily lives, their application to organic synthesis has, so far, been limited. Some particularly useful properties of these include (i) low electronegativity, (ii) a stable oxidation state +2, meaning that can potentially form two covalent bonds with anions, (iii) ability occupy variety coordination sites...

The discovery and development of a new Lewis acid system based on complex formed from niobium(V) methoxide (R)-3,3'-bis(2-hydroxy-3-isopropylbenzyl)-1,1'-binaphthalene-2,2'-diol, novel tetradentate BINOL derivative, is presented. was shown to be extremely effective in promoting the desymmetrative ring opening linear cyclic meso-epoxides using anilines as nucelophiles, delivering corresponding (R,R) anti-amino alcohols good excellent yields (up quantitative) enantioselectivity 96% ee)....

We developed a 1,3-dipolar cycloaddition reaction of azomethine imines with terminal alkynes catalyzed by group 11 metal amides to provide N,N-bicyclic pyrazolidinone derivatives. This afforded the cycloadducts in unique 5,7-disubstituted manner. Furthermore, we succeeded applying this catalysis asymmetric reactions, and desired heterocycles were produced high yields exclusive regioselectivity enantioselectivity. Mechanistic studies elucidated stepwise pathway critical features that...

The development of catalytic asymmetric direct-type reactions less acidic carbonyl compounds such as amides and esters has been a challenging theme in organic chemistry for decades. Here we describe the direct 1,4-addition simple with α,β-unsaturated using amount novel chiral catalyst consisting potassium base macrocyclic crown ether. desired 1,5-dicarbonyl were obtained high yields excellent diastereo- enantioselectivities. This is first example highly enantioselective reaction amides. In...

Catalytic asymmetric aldol reactions of silyl enol ethers with aldehydes (Mukaiyama reactions) have been performed using novel chiral zirconium catalysts. The proceeded in high yields under mild conditions, and anti-adducts were obtained diastereo- enantioselectivities. catalysts first prepared from zirconium(IV) tert-butoxide (Zr(OtBu)4), (R)-3,3'-diiodo-1,1'-binaphthalene-2,2'-diol ((R)-3,3'-I2BINOL), a primary alcohol, small amount water. It was revealed that the alcohol played an...

Catalytic asymmetric hetero Diels−Alder (HDA) reactions using a chiral zirconium complex have been developed. The of aldehydes with Danishefsky's dienes proceeded smoothly to afford the corresponding pyranone derivatives in high yields diastereo- and enantioselectivities presence complex, which was prepared from tert-butoxide, (R)-3,3'-diiodobinaphthol or its derivative, primary alcohol, small amount water. It is noted that 2,3-trans-pyranone were obtained remarkably reaction 4-methyl diene....

The first catalytic asymmetric [3 + 2] cycloadditions of Schiff bases α-aminophosphonates with olefins have been developed. Chiral silver amide complexes bearing (R)-DTBM-SEGPHOS worked well as catalysts for the time, and proline phosphonic analogues were obtained in high yields excellent exo- enantioselectivities.

Silver lining: Highly exo-selective asymmetric [3+2] cycloaddition of α-amino ester Schiff bases with activated olefins proceeds in the presence AgHMDS/1. The including those derived from aliphatic imines successfully reacted to afford corresponding pyrrolidine derivatives high yield exo- and enantioselectivities. EWG=electron-withdrawing group, HMDS=hexamethyldisilazide. Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but...

Abstract 1,4‐addition reactions of alkylazaarenes catalyzed by strong Brønsted bases have been developed for the first time. The desired with α,β‐unsaturated amides proceeded under mild reaction conditions to give 1,4‐adducts in high yields. Both ortho‐ and para‐substituted azaarenes afforded adducts Regioselective di‐ or trimethylpyridine were found be possible depending on acidity α‐hydrogen atoms. Furthermore, a candidate allosteric protein kinase modulators was synthesized two steps. An...

Abstract Catalytic addition reactions of very weakly acidic nonactivated alkylarenes such as toluene and its derivatives were developed by using a strongly basic mixed catalyst system under mild reaction conditions. The with imines alkenes proceeded smoothly proton‐transfer conditions to afford the desired products in good high yields, levels regio‐ stereoselectivity achieved. It was also revealed that asymmetric an alkylarene possible.

Mg(SPh)2 has been found to be a highly active catalyst in photocatalytic alkylation reactions of methylene compounds with nonactivated alkenes. The desired proceeded smoothly afford the corresponding alkylated products high yields low loadings (0.2‐0.3 mol%). This protocol is applicable continuous‐flow system. Notably, magnesium an earth‐abundant metal, and exhibits higher catalytic activity than previously reported LiSPh.

Asymmetric [3+2] cycloaddition of hydrazones to external olefins has been successfully conducted in high yields with enantioselectivities using a chiral zirconium catalyst. These reactions open ways synthetically and biologically important pyrazoline, pyrazolidine, 1,3-diamine derivatives. Further, several experiments suggested that the proceeded via concerted pathways.

Catalytic asymmetric intramolecular [3 + 2] cycloaddition of hydrazone/olefins has been attained. In the presence a chiral zirconium catalyst prepared from alkoxide and BINOL derivative, desired pyrazolidine derivatives were obtained in high yields with selectivities. The products easily converted to 1,3-diamine or beta-aminonitrile by N-N bond cleavage.

The first highly diastereo- and enantioselective catalytic asymmetric 1,4-addition reactions of a glycine Schiff base to β-substituted α,β-unsaturated esters have been developed. reaction pathway was successfully controlled, the desired products were exclusively obtained with high enantioselectivities. product converted 3-substituted glutamic acid derivative by hydrolysis.

Much more reactive than the corresponding benzophenone imines, which have often been used in synthesis of α-amino acids, title compounds undergo Mannich-type reactions with imines presence a catalytic amount base to afford α,β-diamino acid and α,β-diaminophosphonic derivatives high syn diastereoselectivity (see scheme). An asymmetric version reaction is also described. Boc=tert-butoxycarbonyl. Glycine are useful starting materials for acids. For example, glycine esters, type 1 introduced by...

Catalytic asymmetric protonation of chiral calcium enolates was performed. Chiral enolates, prepared in situ from imides and malonates via 1,4-addition the presence catalytic amounts Ca(OEt)2, Ph-PyBox, achiral phenol, were smoothly protonated to afford adducts bearing tertiary carbons high yields with enantioselectivities. The readily converted optically active 2-substituted 1,5-dicarboxylic acid derivatives.

Salt of the earth: The first chiral, coordinative alkaline earth metal catalysts have been developed. These effectively promote catalytic asymmetric additions β-dicarbonyl compounds to nitroalkenes in high yields with enantioselectivities (up 96 %). Detailed facts importance specialist readers are published as ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by authors. Please note: publisher is responsible for content...

Irradiation with UV light, especially UVB, causes epidermal damage via the induction of apoptosis, inflammatory responses, and DNA damage. Various stressors, including induce heat shock proteins (HSPs) induction, particularly that HSP70, provides cellular resistance to such stressors. The anti-inflammatory activity as its inhibition nuclear factor kappa B (NF-kappaB), was recently revealed. These in vitro results suggest HSP70 protects against UVB-induced Here we tested this idea by using...

The development of catalytic asymmetric carbon-carbon bond-forming reactions alkylnitriles that do not have an activating group at the α-position, under proton-transfer conditions, is a challenging research topic. Here, we report direct-type 1,4-addition with α,β-unsaturated amides by using amount potassium hexamethyldisilazide (KHMDS) chiral macro crown ether. desired proceeded in high yields good diastereo- and enantioselectivities. To our knowledge, this first example reaction without any...

We report here efficient catalytic imine–imine cross-coupling reactions based on an umpolung strategy; imine bearing a 9-fluorenyl moiety its nitrogen atom, which acted as nucleophile, reacted with another to afford adduct in high yield. Furthermore, chiral guanidine catalyst for these coupling reactions, and optically active 1,2-diamines were obtained yields enantioselectivities.

Abstract Alkylation reactions are fundamental carbon‐carbon bond‐forming in synthetic organic chemistry. Among them, intermolecular α‐alkylation of carbonyl compounds with alkenes important because they more atom‐economical than the equivalent processes using alkyl halides. However, nonactivated such as 1‐hexene, which can allow use a wide range valuable substrates, have been considered to be very challenging for long time. In this review, radical‐mediated discussed. The examples grouped...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHighly anti-Selective Catalytic Asymmetric Aldol ReactionsHaruro Ishitani, Yasuhiro Yamashita, Haruka Shimizu, and Shū KobayashiView Author Information Graduate School of Pharmaceutical Sciences The University Tokyo, CREST Japan Science Technology Corporation (JST) Hongo, Bunkyo-ku, Tokyo 113-0033 Cite this: J. Am. Chem. Soc. 2000, 122, 22, 5403–5404Publication Date (Web):May 20, 2000Publication History Received13 December 1999Published...