Allylation reaction with various aldehydes

TABLE 9.2. Allylation Reaction with Various Aldehydes... 

Synthesis of a series of novel functionalized achiral and chiral allyl boronates has been recently reported by Ramachandran via nucleophilic SNj -type addition of copper boronate species (generated from the boronates 37, 141, 142 under Miyaura conditions) [115,116] to various functionalized allyl acetates that tvere prepared either via vinylalumination or by Baylis-Hillman reaction with various aldehydes [117]. The resulting allylic boronates bearing an ester moiety (X=OR) were subsequently used for the synthesis of a-alkylidene-/3-substituted-y-butyrolactones by allylboration of aldehydes (Scheme 3.76). 

The indium-mediated allylation carried out with allylstannanes in combination with indium chloride in aqueous medium was reported by Marshall et al.113 Allylindium was proposed as the reaction intermediate. Various aldehydes can be alkylated very efficiently with 3-bromo-2-chloro-l-propene mediated by indium in water at room temperature. Subsequent treatment of the compound with ozone in methanol followed by workup with sodium sulfite provided the desired hydroxyl ester in high yield.114... 

Scheme 6.151 Range of allylic alcohols prepared from 145-catalyzed MBH reactions of2-cyclohexene-l-one with various aldehydes.

Besides allylation reactions, the BINAP/AgOTF complex effectively catalyzes the enantioselective aldol reaction of tin enolates with various aldehydes.315 Under these conditions, a wide range of aldol products were smoothly formed with good to high yields and enantioselectivities (Scheme 104). 

When the aldol reaction furnishes an intermediate oxonium ion, a Prins cydization may ensue in the case where a suitable internal nucleophile is present that intercepts this oxonium ion. Rychnovsky et al. have developed this strategy into a powerful tool for the straightforward synthesis of tetrahydropyrans [7]. Thus, enol ether 15 attached to an allyl silane reacted with various aldehydes under BFj activation to produce 2,6-cis-substituted-4-methylene tetrahydropyrans 16 in good to very good yields (Table 8.2). 

A carbonyl yllde reaction Is demonstrated In eq 10. The dIazoester from reaction of compound (1) and allyl alcohol Is subsequently treated with MesSlOTf. The unsaturated sllyldlazoester reacts with various aldehydes or acetone catalyzed by rhodlum(II) perfluorobutyrate to afford 1,3 dioxolan 4-ones in moderate yields via carbonyl yUde intermediates (eq 10). ... 

Allylation adducts of ( )-Y-(dimethylphenylsilyl)allylboronate 47 selectively undergo addition reactions with aldehydes. Lewis acid catalyzed [3 + 2] cycloaddition reaction of these allylsilanes with various aldehydes, e.g., 55, provides tetrahydrofuran adducts with high diastereoselectivity. ... 

A-Sulfonylaldimines produced by condensation of SES-NFI2 with various aldehydes are converted into enantiomerically enriched aziridines upon reaction with certain sulfur ylides. The same types of aldimines undergo [3 4- 2] cycloaddition reactions with 2,3-butadienoates in the presence of triphenylphosphine to give 2,5-dihydrop3TToles, while that derived from SES-NSO and ethyl glyoxylate reacts efficiently with chiral sulfonimidoyl substituted bis(allyl)titaniumcorr5)lexes to give /3-alkyl-)/,5-unsaturated a-amino acid derivatives. ... 

Chiral hydroxyl-functionalized allylic silanes were obtained by the reaction of various aldehydes and chiral double allylating reagent (11) with high enantioselec-tivities (up to 98% ee) and excellent E/Z ratio ( > 25 1 to > 30 1) using 1 equivalent of BP3 OEt2 as a Lewis acid promoter. The resulting chiral allylic silanes can be... 

The o, )-unsaturated ester 7 can be transformed reductively into the p,Y-unsaturated system 8 in high yield using magnesium in methanol J Reaction of the chiral crotyl silane 9 with various aldehydes and acetals offers a diastereoselective approach to branched P,Y-unsatuiated esters, as in the example in Scheme 2, and, as indicated, stereospecific allylic rearrangement gave the a,p-unsaturated system. Similar reactions were also described using the C-2 epimer of 9. ... 

The dianions derived from furan- and thiophene-carboxylic acids by deprotonation with LDA have been reacted with various electrophiles (Scheme 64). The oxygen dianions reacted efficiently with aldehydes and ketones but not so efficiently with alkyl halides or epoxides. The sulfur dianions reacted with allyl bromide, a reaction which failed in the case of the dianions derived from furancarboxylic acids, and are therefore judged to be the softer nucleophiles (81JCS(Pl)1125,80TL505l). 

A new method has been developed for the synthesis of ( )-3-methyl Baylis-Hillman-type adducts with high E/Z (>93%) selectivity in modest to good yields. The process consists of two steps an indium-mediated allylation reaction and a simple base-catalyzed isomerization step (Eq. 8.61). Various aldehydes were allylated with allyl bromides using indium under very mild conditions in aqueous media and thus converted to the Baylis-Hillman-type adducts.150... 

The complex -Tol-BINAP-AgF (/>-Tol-BINAP - 2,2 -bis(di-/)-tolylphosphanyl)-l,l -binapthyl) catalyzes the asymmetric addition of allylic trimethoxysilanes to aldehydes (Equation (7)).7 3 The process can provide various optically active homoallylic alcohols with high enantioselectivity (up to 96% ee) and a remarkable 7 and anti- selectivities are observed for the reaction with crotylsilanes, irrespective of the configuration of the double bond ... 

The criss-cross addition of azines of aromatic aldehydes with various electron-deficient olefins in which the double bond is terminal, for example, methyl acrylate, acrylonitrile, or in which allylic substituents do not sterically hinder the reaction, for example, maleic anhydride, is well known and was duly covered in CHEC-II(1996)<1996CHEC-II(8)747>, as well as in a review <1997ALD97>. Recently, the reaction has been used for the preparation of hyperbranched polymers <1998MI2655, 2002MAC712>. 

Kondo and Watanabe developed allylations of various types of aldehydes and oximes by using nucleophilic (7r-allyl)ruthenium(ll) complexes of type 154 bearing carbon monoxide ligands (Equation (29)).345 These 73-allyl-ruthenium complexes 154 are ambiphilic reagents and the presence of the carbon monoxide ligands proved to be essential to achieve catalytic allylation reactions. Interestingly, these transformations occur with complete regioselectivity only the more substituted allylic terminus adds to the aldehyde. 

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