Tris acetaldehyde preparation

Gassman and co-workers developed a synthetic route from anilines to indoles and oxindoles which involves [2.3]-sigmatropic rearrangement of anilinosul-fonium ylides. These can be prepared from Ai-chloroanilines and ot-thiomcthyl-ketones or from an aniline and a chlorosulfonium salt[l]. The latter sequence is preferable for anilines with ER substituents. Rearrangement and cyclizalion occurs on treatment of the anilinosulfonium salts with EtjN. The initial cyclization product is a 3-(methylthio)indole and these can be desulfurized with Raney nickel. Use of 2-(methylthio)acetaldehyde generates 2,3-unsubstituled indoles after desulfurization[2]. Treatment of 3-methylthioindoles with tri-fiuoroacetic acid/thiosalieylie acid is a possible alternative to Raney nickel for desulfurization[3]. 

A reagent more reactive than tris(dimethylamino)arsine employed by Weingarten and White 39) was tetrakis(dimethylamino)titanium (145). With this compound it was possible to prepare N,N-dimethyl(l-isopropyl-2-methylpropcnyl)amine (147) from diisopropyl ketone. Weingarten and White 39) have suggested a possible mechanism for this reaction (see p. 88). If benzaldehyde 39,111), formaldehyde 111), or acetaldehyde 39) is used, the corresponding gem diamine or aminal (143) is formed. 

On a laboratory scale, one of the favored catalyst is the benzyl tri-n-butyl ammonium chloride (BTBAC). The most important reagent, a-chloroethyl chloroformate ( ACE-CI ), typically is isolated in 96% yield by stirring acetaldehyde with phosgene (1.1 eq.) neat for an hour in the presence of 3 mol. % BTBAC. Even chloromethyl chloroformate can be prepared using this process, but it is essential to introduce the monomeric gaseous formaldehyde into the... 

To a solution 0.46 g 2-[(lS,4S,5R,6S)-4,5,6-tris(benzyloxy)cyclohex-2-enyloxy]-acetaldehyde (1 mmol) in 5 mL anhydrous toluene was added a solution of 0.12 g N-benzyl-hydroxylamine (1.1 mmol, prepared from the hydrochloride acid with 0.1 mL triethylamine) in 2 mL anhydrous dichloromethane. The reaction mixture was stirred at 20°C for 2 h. Removal of the solvents under reduced pressure furnished a residue, which was chromatographed to give 0.4 g (2fl5,4aS,5S,6S,7R,7aR,7 R)-2-benzyl-5,6,7-tris(benzyl-oxy)octa-hydro-2H-furo[4,3,2-c,d][l,2]benzisoxazole as a colorless wax, in a yield of 70%. Rf = 0.45 (toluene/ethyl acetate, 5 1). a] = 86.14 (c = 1.0, CHCI3). 

The reaction of D-glucose diethyl dhhioacetal with addic acetone fiimished the two diacetonides 6 and 7 in the ratio 3 1 thdr structures which were proposed thirty years ago without proof (P.A.J. Gorin, Can. J. Chem., 1965, 43, 2078) have now been firmly established with the help of extensive n.m.r. spectroscopic analysis. Experimental details fi)r the one-pot preparation of l,2-0-isopropylidene-a-l> xylofiiranose in 80% yield fiom D-xylose have beoi published/ 2, 3 4,6 ,4, 6 -Tri-0-cyclohcxylidene-(X,a -trehalose was an important synthetic precursor of mycobacterial 2,3-di-O-acyl derivatives of oc,a -trehalose in connection with this preparation the lohe 7iidenation, isopropylidenation, and ethylidenation of this disaccharide by use of ethoj rcydohexane, 2-methoxypropene, and acetaldehyde, respectively, in acidic media have been studied in some detail/... 

Other attempts to prepare 2,4,6-tris(trifluoromethyl ) acetophenone have also been met only with very limited success (28)i 1) No reaction was observed when 1,3,5-tris trifluoromethyl)-benzene was treated with acetyl chloride in the presence of anhydrous AICI3 ( vide supra), 2) The secondary alcohol RfCH(OH)CH3 can be prepared from RpLi and acetaldehyde. However, it was found impossible to oxidize this alcohol with Jones reagent (Cr ). Although IR spectra showed some evidence... 

The synthesis of disilenyllithium precursor from disilene and lithium naphthalerude is described in Chapter 6.2.1. Tris(3,5-di-tbutylphenyl) acetaldehyde was prepared from trityl chloride according to the procedure presented in Scheme 6.2.2.1. Trityl chloride can be prepared from commercially available 1,3,5-tri-tbutylphenyl by reported procedure (7,8). 

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