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The Pd(PPh2)4-catalyzed coupling reaction of alkenyl-disiamylboranes with furfuryl chloride in the presence of f-BuOK afforded (E)-furfurylalkenes stereospecifically in good yields.

Pd-catalyzed cross-coupling reactions of chloropyrimidines with alkenylboronic acids readily proceed to give the corresponding alkenylpyrimidines in high to excellent yields. The coupling reaction of 2,4-dichloropyrimidine or 2,4,6-trichloropyrimidine with one equivalent of alkenylboronic acid occurred more easily on 4-position than on 2-position, which implied that the reaction is highly regioselective. The reaction is stereospecific since the configuration of C=C remained intact. The preliminary study on the cross-coupling reactions of 2,4,6-trichlorotriazine with one equivalent of arylboronic acids showed that the reactions afforded the monosubstituted triazines in moderate yields. The effect of steric hindrance of the substitutents on the reactions was found.

An efficient stereoselective aza-Henry reaction of N-tosyl imine, catalyzed by the coordination of diethylzinc with a chiral semi-aza-crown ligand, with moderate to high ee (up to 83%) is reported.

The Suzuki–Miyaura type cross‐coupling reactions of various chloropyrimidines with stereodefined alkenylboronic acids giving the corresponding alkenyl‐substituted pyrimidines were studied. The experiments discovered that the reaction is stereospecific and highly regioselective. In the coupling of 2,4‐dichloropyrimidine and 2,4,6‐trichloropyrimidine, the reaction occured at 4‐position prior to 2‐position.

Ethyl (2 E ,4 E )-3-trifluoromethyl-2,4-dienoates 1a – e and ethyl ( E )-3- trans -alkylcyclopropyl-4,4,4-trifluoro-2-butenoates 2a – e were prepared from the trans -alkenylboronic acids 3a – e and the trans -cyclopropylboronic acids 4a – e with ethyl ( Z )-3-iodo-4,4,4-trifluoro-2-butenoate ( 5 ) by the Suzuki cross-coupling reaction in high yields (88–95%). The configurations of both 3a – e or 4a – e and 5 were retained in the reaction.

Aryl amides were synthesized by the palladium catalyzed cross-coupling reaction of α-bromoacetamides with arylboronic acids in good yields. Both electron-donating and electron-withdrawing substituents on the aromatic ring are found to be compatible. The addition of Cu 2 O and PPh 3 was found to be essential for good reaction yields.

Stereodefined cyclopropyl substituted acrylate esters were selectively reduced to the corresponding propionate esters by sodium borohydride in methanol/DMF with a catalytic amount of CoCl 2 without the opening of the cyclopropane ring. The configuration and chirality of the stereodefined cyclopropyl function were retained in the reaction. Combined with the cross-coupling reaction of stereodefined cyclopropylboronic acids with bromoacrylate esters or alkenyl triflates, the reaction method provides a novel route to stereodefined 3-cyclopropyl propionate ester, an important subunit existing in a wide range of natural compounds.

[reaction: see text] The stereocontrolled dehydrobromination of 1,2-dibromoethyl carboxylates giving (Z)-2-bromovinyl carboxylates could readily be approached by using DBU and a catalytic amount of hydroquinone as a base at -78 degrees C. The first investigation on the Suzuki-type cross-coupling of (Z)-2-bromovinyl carboxylates as electrophiles with stereodefined alkenylboronic acids provides a novel method for the construction of (Z,E)- or (Z,Z)-conjugated alkadienyl carboxylate moieties, which are often present in a range of natural products.

A novel method for the synthesis of stereodefined cyclopropyl-substituted alkenes, based on the Suzuki-type cross-coupling reaction between cyclopropylboronic acids and various alkenyl triflates, is described. It was found that the environment of the alkenyl triflate plays an important role in the reaction, and that the use of an appropriate base can make the reaction proceed readily to give stereodefined cyclopropyl-substituted alkenes in good to high yield.

The first Tl2CO3 or Ag2O assisted Suzuki-type cross-coupling of stereodefined cyclopropylboronic acids with haloalkenes without electron-drawing groups to give the corresponding stereodefined cyclopropyl-substituted alkenes in good yields is described. The configurations of both cyclopropyl and alkenyl functions were retained in the reaction.

The Suzuki-type coupling reaction of cyclopropylboronic acids (esters) with benzyl bromides readily takes place by using Ag2O with KOH as the base. The reaction rate and the cross-coupling product yields of cyclopropylboronate esters of ethylene glycol or propane-1,3-diol were higher and better than those of cyclopropylboronic acids. However, the coupling reaction of the cyclopropylboronate esters of glycol with larger substituents was sluggish. The highly optically active benzyl-substituted cyclopropanes could be obtained by the coupling reactions of corresponding optically active cyclopropylboronate esters with benzyl bromides. A novel, ideal method for preparing stereo-defined benzyl-substituted cyclopropanes, especially optically active benzyl-substituted cyclopropanes, is described here.

In the presence of Pd(PPh3)4, NaBr and KF·2H2O the cross-coupling reaction of heteroaryl triflates with trans-cyclopropylboronic acids proceeds readily to give pure trans-cyclopropyl heteroarenes in moderate to good yields. The X-ray crystallography of compound 3g and 1H-NMR spectra of all products show that the configuration of the cyclopropyl group was retained during the reaction. Under the same reaction conditions, highly optically active cyclopropyl-substituted heteroarenes (up to 94% ee) were obtained by cross-coupling of heteroary/triflates with enantiomerically enriched cyclopropylboronic acids.

The Suzuki-type cross-coupling reaction of stereodefined cyclopropylboronic acids with N-heterocycl bromides was investigated. In the appropriate conditions the coupling reactions readily underwent to afford stereocontrolled cyclopropyl substituted N-heterocycles in moderate to good yields The configuration of cyclopropylboronic acids retained during the reaction.

The Suzuki-type coupling reaction of arylboronic acids ( 1 ) with 2-bromo-3,3,3-trifluoropropene ( 2 ) in the presence of a catalytic amount of dichlorobis(triphenylphosphine)palladium {PdCl 2 (PPh 3 ) 2 } and a base can easily give α-(trifluoromethyl)styrenes ( 3 ) in good yields. It was also found that 1,2-dibromo-3,3,3-trifluoropropane ( 4 ) underwent dehydrobromination in the presence of KOH, and subsequently, palladium-catalyzed cross-coupling with 1 to directly afford 3 in a one pot manner in excellent yields.

The first palladium-catalyzed cross-coupling reaction between substituted arylboronic acids and chloroformate or carbamoyl chloride is described. One-carbon homologation from arylboronic acids was achieved to give corresponding esters or amides in good yields.

The reactions of 2-chloromethylthiophene (an analog of a benzyl halide) with lithium trialkylalkynylborates gave, after protonation, E-alkenes with a (2-thenyl) substituent in good yields, and the reaction stereo-selectivity was different from that of the reaction of benzyl bromide with an alkynylborate.

Optically active cyclopropanes (e.g. 1) can be prepared by the use of tartaric acid derivatives as chiral auxiliaries in the palladium-catalyzed cross-coupling of optically active cyclopropylboronic acids with electrophiles. The absolute configuration of the chiral carbon atom is retained, and the reaction proceeds with good yields and enantiomeric excesses. R=H, p-Ph, o-CO2 CH3 , p-CO2 CH3 , p-NO2 , o-OCH3 , m-OCH3 .

[reaction: see text] The palladium-catalyzed cross-coupling reaction of cyclopropylboronic acids with acyl chlorides was achieved by the combination of Ag(2)O and K(2)CO(3) as the base. Highly enantiomerically enriched cyclopropyl ketones (ee90%) were also obtained by the reaction of corresponding chiral cyclopropylboronic acids.

A simple and efficient synthesis of N-sulfonyl ketimines through a Pd-catalyzed cross-coupling reaction between organoboronic acids and tosylbenzimidoyl chlorides under mild conditions has been developed.

Optically active cyclopropanes (e.g. 1) can be prepared by the use of tartaric acid derivatives as chiral auxiliaries in the palladium-catalyzed cross-coupling of optically active cyclopropylboronic acids with electrophiles. The absolute configuration of the chiral carbon atom is retained, and the reaction proceeds with good yields and enantiomeric excesses. R=H, p-Ph, o-CO2 CH3 , p-CO2 CH3 , p-NO2 , o-OCH3 , m-OCH3 .

4-Substituted 1,2-oxaborol-2(5H)-ols were prepared through copper-catalyzed carbomagnesation of propargyl alcohol, followed by the transmetallation of magnesium to boron in a one-pot procedure. The Suzuki-Miyaura cross-coupling of these new 2,2-disubstituted alkenylboronic acids with aryl halides afforded stereodefined 2,3-disubstituted allyl alcohols in good to excellent yields.

The effect of coordination on the reaction of N-tosyl imines and diethylzinc was studied in detail. It showed that there was strong coordination between N-tosyl imine and diethylzinc. Due to this coordination, N-tosyl imines could be reduced directly through the β-H transferring mechanism by diethylzinc in nonpolar solvents to afford the corresponding secondary amines in excellent yields at mild conditions. The coordination of diethylzinc and N-tosyl imine was hindered by reacting in polar solvents or adding TMEDA to the reaction, it afforded ethylating product partially or exclusively.

[reaction: see text] Stereospecific cyclopropanation of alkenylboronic esters of pinacol followed by in situ treatment with excess KHF(2) afforded the corresponding potassium cyclopropyl trifluoroborates in high yields, which then underwent Suzuki-Miyaura cross-coupling reactions with aryl bromides to give cyclopropyl-substituted arenes in good yields with retention of configuration. This promises to be a useful method for the synthesis of enantiomerically pure cyclopropanes.

A novel method for the synthesis of stereodefined cyclopropyl-substituted alkenes, based on the Suzuki-type cross-coupling reaction between cyclopropylboronic acids and various alkenyl triflates, is described. It was found that the environment of the alkenyl triflate plays an important role in the reaction, and that the use of an appropriate base can make the reaction proceed readily to give stereodefined cyclopropyl-substituted alkenes in good to high yield.

Copper(I) oxide can effectively co-catalyze the Suzuki type cross-coupling reactions of arylboronic acids with ethyl bromoacetate. As an alternative protocol for introducing the methylenecarboxy group into functionalized molecules, this reaction occurs in the absence of highly toxic thallium compounds or special ligands and should be convenient and practical.

The reaction of allylcarbonate with lithium trialkylalkynylborates catalysed by Pd(PPh 3 ) 4 , affords 1,4-alkadienes in good yields and high stereoselectivity.

Chloromagnesium trialkylvinylborate, (R3BCHCH2)MgCl, on reaction with carbon dioxide under pressure, followed by oxidation with alkaline hydrogen peroxide, gives a β-hydroxycarboxylic acid.