Tris Reformatsky reactions

The indium-mediated Reformatsky reaction of phenyl a-bromoalkanoates with ketones or aldehydes gives di-, tri-, and tetrasubstituted /3-lactones (Table 21).327-329 A similar reaction of imines with ethyl bromoacetate gives 3-unsubstituted /3-lactams (Equation (83)).330 331... 

REFORMATSKY REACTION Chlorotrime-thylsilane. Tri-n-butyltinlilhium-Diethylal-uminum chloride-Zinc. Zinc-Graphite. 

REDUCTIVE DEOXYGENATION OF ALCOHOLS AND KETONES N.N.N .N1-Tetramethyldiamidophosphorochloridate. REFORMATSKY REACTION Ethyl tri-chloroacetate. Lithium diisopropylamide. REVERSE WITTIG REACTION Triphenyl-arsine oxide. 

Indium enolates, prepared conveniently by transmetalation of hfhium enolates with IriCl j, react wifh aldehydes to give fhe corresponding -hydroxy esters [80]. Ultrasound irradiation promotes fhe Reformatsky reaction of aldehydes and ethyl bromoacetate wifh indium [81]. Indium-mediated Reformatsky reaction of phenyl a-bromoalkanoates wifh ketones or aldehydes gives di-, tri-, and tetrasubstituted -lactones (Scheme 8.57) [82]. Indium-mediated reaction of imines with ethyl bromoacetate gives 3-unsubstituted -lactams (Scheme 8.58) [83]. An indium-Refor-matsky reagent prepared from 2-(chlorodifluoroacetyl)furan couples with aldehydes (Scheme 8.59) [84]. 

In 1975, the Tumor Research Group of the Chinese Academy of Medical Science (47) reported a short synthesis of harringtonine (2) as shown in Scheme 19. Treatment of the olefinic pyruvate 148, obtained from the reaction of cephalotaxine and the corresponding acid, with mercuric tri-fluoroactate, followed by reduction with sodium borohydride yielded the known hemiketal 140. Reformatsky reaction of 140 with methyl bromo-acetate yielded harringtonine (2). 

An alternative strategy for this type of olefination is the Reformatsky reaction, which, when mediated by tri-n-butyl stibine, directly gives excellent yields of (E)-a,B-unsaturated esters with or... 

A novel Reformatsky reaction using ethyl bromoacetate-zinc-titanium tetrachloride has been applied with l-0-acetyl-2,3,5-tri-0-benzoyl-p-D-ribose to give the 3-linked product (159)." Compound (160), obtained by use of a Grignard reagent and a glycosyl chloride, has been made as a nucleoside analogue and incorporated into oligonucleotides for studies of duplex stability." ... 

The modifications of the Gilman-Speeter reaction include the activation of zinc by tri-methylsilyl chloride (TMSCl) and the application of lithium ester enolate" or lithium thioester enolate as the substitute for the traditional Reformatsky reagent. In these modifications, it was found that TMSCl-activated zinc is much more effective in promoting the reaction between ethyl bromoacetate and Schiff bases. In addition, in the presence of a chiral ether ligand, the reaction between lithium ester enolate and imines affords 0-lactams of high enantiomeric excess, probably due to the formation of a ternary complex reagent. " The enantioselectivity and reactivity of the ternary complex depend on the size and nature of the lithium amide used. For example, the lithium amide from 2,2,6,6-tetramethylpiperidine (LTMP) is unfavorable for this reaction." ... 

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