Lithium aluminum hydride-boron trifluoride etherate

Lithium aluminum hydride-3-0-Benzyl-l,2-0-cyclo-hexylidene-a-D-glucofuranose complex1 [1, 599, before Lithium aluminum hydride-Boron trifluoride etherate]. 

Related Reagents. See entries for other Lewis Acids, e.g. Zinc Chloride, Aluminum Chloride, 1Uanium(IV) Chloride-, also see entries for Boron Trifluoride (and combination reagents), and combination reagents employing Boron Trifluoride Etherate, e.g. ButyUithium—Boron Trifluoride herate, Cerium(III) Acetate-Boron Trifluoride Etherate, Lithium Aluminum Hydride-Boron Trifluoride Etherate, Methylcopper-Boron Trifluoride Etherate,... 

Related Reagents. Lithium Aluminum Hydride-(2,2 -Bipy-ridyl)(l,5-cyclooctadiene)nickel Lithium Aluminum Hydride-Bis(cyclopentadienyl)nickel Lithium Aluminum Hydride-Boron Trifluoride Etherate Lithium Aluminum Hydride-Cerium(III) Chloride Lithium Aluminum Hydride-2,2 -Dihydroxy-l, E-binaphthyl Lithium Aluminum Hydride-Chromium(III) Chloride Lithium Aluminum Hydride-Cobalt(II) Chloride Lithium Aluminum Hydride-Copper(I) Iodide Lithium Aluminum Hydride-Diphosphoms Tetraiodide Lithium Aluminum Hydride-Nickel(II) Chloride Lithium Aluminum Hydride-Titanium(IV) Chloride Titanium(III) Chloride-Lithium Aluminum Hydride. 

Reduction of aromatic carboxylic acids to alcohols can be achieved by hydrides and complex hydrides, e.g. lithium aluminum hydride 968], sodium aluminum hydride [55] and sodium bis 2-methoxyethoxy)aluminum hydride [544, 969, 970], and with borane (diborane) [976] prepared from sodium borohydride and boron trifluoride etherate [971, 977] or aluminum chloride [755, 975] in diglyme. Sodium borohydride alone does not reduce free carboxylic acids. Anthranilic acid was reduced to the corresponding alcohol by electroreduction in sulfuric acid at 20-30° in 69-78% yield [979],... 

Thiol esters can be reduced to sulfides or aldehydes. Alone generated from lithium aluminum hydride and boron trifluoride etherate [1099] or aluminum chloride [1100] in ether reduced the carbonyl group to methylene and gave yi-9y /o yields of sulfides. Phenyl thiolbenzoate failed to give the sulfide, and phenyl thiolacetate gave only an 8% yield of ethyl phenyl sulfide [1100]. 

Neopentyl sulfides have been prepared by alkylation of sodium sulfide with neopentyl tosylate in high-boiling polar solvents,4,5 or in low yields by reduction of alkyl 2,2-dimethylpropanethioate with the combination of lithium aluminum hydride and a large excess of boron trifluoride-etherate. ... 

Diphenylphosphine)lithium, 126 Nickel boride, 197 Samarium(II) iodide, 270 to 1,2-disubstituted compounds B-3-Pinanyl-9-borabicyclo-[3.3.1]nonane, 249 Titanium(III) chloride, 302 of phosphorus compounds Lithium aluminum hydride-Cerium(III) chloride, 159 of sulfoxides and sulfones Sodium iodide-Boron trifluoride ether-ate, 282... 

Dihydroxylation of the stilbene double bond in the trans isomers of Combretastatin A-1 and A-4 produced diols which by treatment with boron trifluoride in ethyl ether [44] or with trifluoroacetic acid [17] resulted in pinacolic rearrangement to produce an aldehyde. The aldehyde was converted in a variety of derivatives, as illustrated in the Scheme 20, via the following reaction sequence reduction with sodium borohydride to primary alcohol which was derivatized to the corresponding mesylate or tosylate, substitution with sodium azide and final reduction to amine with lithium aluminum hydride. Alternatively the aldehyde was converted to oxime which was catalitically hydrogenated to amine [17]. 

Reduction of 2-hydroxycyclobutanone by lithium aluminum hydride gave a 1 1 mixture of cis- and trans-cyclobutane-1,2-diols (80%). Slow distillation of the mixture of these diols in the presence of a catalytic amount of boron trifluoride-diethyl ether complex heated to 230°C in a metal bath gave cyclopropanecarbaldehyde (1) in 65-80% yield, providing an easy route to this aldehyde. Heating the diols in benzene in the presence of p-toluenesulfonic acid was less effective moreover, formation of the cyclopropanecarbaldehyde acetal subsequently occurred under these conditions. ... 

BORON TRIFLUORIDE DIETHYL ETHERATE (109-63-7) Combustible liquid (flash point 147°F/64°C). Forms unstable peroxides, unless inhibited. Violent reaction with moist air, water, steam, forming hydrogen fluoride. Violent reaction with oxidizers, etherral lithium aluminum hydride, and other powerful reducing agents. Attacks metals, glass, concrete in the... 

The Harley-Mason approach to the Aspidosperma skeleton was discussed in Volume XI (p. 225), and very brief mention was made of the successful synthesis of aspidospermidine (249) using this route (241). In view of the complication involving cis/trans C/D ring stereochemistry involved in a number of other approaches, it is amazing that the Harley-Mason approach should be stereoselective. The process in question is typically reaction of the hydroxyester 560 with tryptamine to give a compound (561) having a sero-ebumane skeleton. When this compound is treated with 40% sulfuric acid or boron trifluoride etherate at 100°, the indolenine lactam 562 is produced. Lithium aluminum hydride reduction then gives racemic aspidospermidine (249 Scheme 33). 

The technique of cyclization of a 1,4,5,6-tetrahydropyridine to an indole nucleus is already familiar (191), and this method was extended to compound 570. Treatment of 570 with boron trifluoride-etherate gave the keto lactam 571 in 62% yield. Thioketalization and Raney nickel reduction gave a lactam (572) which, upon lithium aluminum hydride reduction, gave 2Q-iso-20-deethylaspermidine (573). However, although the initial keto lactam 571 possessed the required C/D cis stereochemistry, under the thioketalization conditions C-20 isomerization occurred to give the more stable C/D trans ring juncture. 

The ability to rearrange substituted tetrahydro-)3-carbolines into indolenines under appropriate acidic conditions has led to a synthesis of 16-methylaspidospermidine from an intermediate in another total synthesis of the eburnamine-type alkaloids (Chart III). This route to d -eburnamine is an interesting variant of an eax lier synthesis of eburn-amonine (7). The boron trifluoride-etherate rearrangement and ring closure of the tetracyclic intermediate appeared to have given an entirely homogeneous product and the subsequent lithium aluminum hydride... 

Treatment of 649 with ethanedithiol in the presence of boron trifluoride etherate results in acetal—thioacetal interchange at C-6 and subsequent lactonization of the 4)5-hydroxyl group with the r/-butyl ester, thus furnishing 651 in 83% yield. Reduction of the lactone to a lactol, protection with a MOM group, hydrolysis of the thioacetal, and reduction of the ketone with lithium aluminum hydride gives 653 as a single product. After benzoylation of the alcohol, conversion of the OMOM derivative to carboxamide (OMOM —> OAc CN — CONH2) affords 140 as a 10 1 mixture of isomers. 

The reduction of 569e with lithium aluminum hydride followed by monoprotection with er -butyldimethylsilyl chloride and Dess-Martin oxidation of the free hydroxyl group to an aldehyde affords 610. An aldol reaction of 610 with ( S)-(y-alkoxyallyl)stannane (611) in the presence of boron trifluoride etherate provides exculsively, in 80% yield, the alcohol 612. Ozonolysis of the olefin followed by sodium borohydride reduction affords diol 613, which is converted to acetonide 614 (Scheme 135). Interestingly, alcohol 612, the double bond of which is susceptible to stereocontrolled introduction of hydroxyl groups, could lead to o)-deoxy sugars [197]. 

Related Reagents. Acrylonitrile boron trifluoride etherate ceric(rV) ammonium nitrate 2,3-dichloro-5,6-dicyano-/7-benzo-quinone drrhodium(II) tetrakis[methyl 4(/J)-2-oxazolidinone-4-carboxylate] drrhodium(II) tetrakis[(5)-Ai-phthaloyl-r-leucinate] DMSO epichlorohydrin lithium aluminum hydride methyl acrylate methyl lithium methyl triflate tetrabuty-lammonium fluoride trimethylsilyl chloride rhodium(II) tetraacetate. 

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