Selective allylation of carbonyl compounds in aqueous media

Einhorn, Cathy; Luche, Jean‐Louis

doi:10.1016/0022-328x(87)85005-2

Cited by 144 publications

(55 citation statements)

References 29 publications

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“…Subsequently this imine 6 could be easily attained from condensation of R-(+)-Glyceraldehyde 5 and allyl amine (Scheme 1). The synthesis of title compound initiates from a wellknown carbohydrate precursor (R)-2,3-isopropylidene glyceraldehyde 5, which can be easily prepared from commercially available D-mannitol [23][24][25][26]. As depicted in Scheme 2, condensation of allylamine with glyceraldehyde 5 gave imine 6, which was then further converted to secondary amine 7 by zinc mediated Barbier allylation [13,[27][28][29][30][31][32] protocol with good diastereoselectivity (anti/syn = 9 : 1) in 80% yield.…”

Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of (+)-α-Conhydrine from R-(+)-Glyceraldehyde

Penumati

Nagaiah

2014

Organic Chemistry International

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Stereoselective synthesis of (+)--Conhydrine was accomplished from protected (R)-(+)-glyceraldehyde, a familiar carbohydrate predecessor. Our synthetic strategy featured the following two key reactions. One is Zn-mediated stereoselective aza-Barbier reaction of imine 6 with allyl bromide to afford chiral homoallylic amine 7, and the other is ring-closing metathesis. IntroductionExploiting natural products to ascertain a lead has always been important technique in drug discovery. Nature provides a rich source of bioactive compounds with significant biological activity and has therefore received considerable attention from the synthetic organic communities. The major class of biologically active molecules containing substituted piperidines has been widely present in the nature. The efforts to find a short and high yielding synthetic route for this class of natural products were always a contemporary interest. Some of the hydroxylated piperidine alkaloids are reported to be highly toxic and have drawn significant attention through their biological activity [1][2][3].Conhydrine is one of the classes of alkaloids which were isolated by Wertheim from the poisonous plant, Conium maculatum L [4], in 1856. A highly fatal toxin causing paralysis of the skeletal musculature, 2-(1-hydroxyalkyl)-piperidine is a recurrent unit in many alkaloids such as Homopumiliotoxin 223 G 2, Slaframine 3, and Castanospermine 4 (Figure 1). Since the pioneering studies on the synthesis of (+)--Conhydrine 1 by Galinovasky and Mulley [5], various methods have been reported normally based on auxiliary supported or chiral pool approach [6][7][8][9][10][11][12][13][14][15][16][17][18].In view of the interesting biological and structural properties, especially the nitrogen containing alkaloids makes (+)--Conhydrine 1 as an attractive and challenging synthetic target. As mentioned above (+)--Conhydrine 1 was synthesized from various synthetic routes which involve a large number of steps to obtain the target molecule. Thus development of new methods for the synthesis of (+)--Conhydrine 1 constitutes an area of current interest. Herein, an efficient synthesis of (+)--Conhydrine 1 has been designed starting from 2,3-isopropylidene-R-(+)-Glyceraldehyde, by means of Zn-mediated stereoselective Barbier allylation as a key step, which was developed previously for the synthesis of different natural products in our laboratory [19][20][21][22]. To the best of our knowledge synthesis of (+)--Conhydrine via aza-Barbier zinc allylation was not reported so far. Materials and MethodsAll reagents were purchased from Aldrich (Sigma-Aldrich, Bangalore, India). All reactions were monitored by TLC, performed on silica gel glass plates containing 60 F-254. Column chromatography was performed with Merck 60-120 mesh silica gel. IR spectra were recorded on a PerkinElmer RX-1 FT-IR system.

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Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of (+)-α-Conhydrine from R-(+)-Glyceraldehyde

Penumati

Nagaiah

2014

Organic Chemistry International

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“…[2,5] Therefore, traditional procedures for synthesis of homoallylic amines involve the exclusion of air and moisture and the use of dry solvent tetrahydrofuran (THF) or CH 3 CN, alternative media such as polyethylene glycol (PEG) or poly(propylene) glycol (PPG), and highly reactive organometallic reagents. [6][7][8][9] However, some of the methods employed earlier are associated with certain drawbacks such as long reaction times, unsatisfactory yields, and requirement for a catalyst or a nitrogen atmosphere.…”

Section: Introductionmentioning

confidence: 98%

Solvent-Free Addition Reaction of Allylzinc Bromide and Aldimines

Zhang

Han

Yan

2012

Synthetic Communications

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“…Reactions ''on water'' [13] (in the absence of nanoparticles) do not give satisfactory yields of desired alkylated arenes. A crucial component in this process is diamine TMEDA (N,N 0 -tetramethylethylenediamine), its role seemingly multifaceted in that it (a) may activate the zinc surface prior to oxidative addition, akin to the role played by NH 4 Cl [14,15]; (b) stabilizes the catalytic amounts of newly formed primary organozinc species by ligation, and (c) adds lipophilicity to the organometallic further enhancing its migration into the hydrophobic micellar interior. In the case of secondary alkyl iodides that are far more prone to Zn insertion, a change in diamine (to N,N 0 -tetraethylethylenediamine) was required to achieve good yields [13].…”

Section: Introductionmentioning

confidence: 99%