DIBAL reduction with

Detty published the first example of the titled approach in his pioneering work on teluropyrans (88MI1). The hexafluorophosphate 76 was reduced with diisobutyl aluminium hydride (DIBAL-H) to a 93 7 mixture of isomeric teluropyrans 77 and 78 accompanied by traces (ca. 1%) of the dimeric product 80. The latter was also obtained after the electrochemical reduction of 76 via radicals 79 or by a modification of the reduction with DIBAL-H (Scheme 5). 

To investigate the feasibility of employing 3-oxidopyridinium betaines as stabilized 1,3-dipoles in an intramolecular dipolar cycloaddition to construct the hetisine alkaloid core (Scheme 1.8, 77 78), a series of model cycloaddition substrates were prepared. In the first (Scheme 1.9a), an ene-nitrile substrate (i.e., 83) was selected as an activated dipolarophile functionality. Nitrile 66 was subjected to reduction with DIBAL-H, affording aldehyde 79 in 79 % yield. This was followed by reductive amination of aldehyde x with furfurylamine (80) to afford the furan amine 81 in 80 % yield. The ene-nitrile was then readily accessed via palladium-catalyzed cyanation of the enol triflate with KCN, 18-crown-6, and Pd(PPh3)4 in refluxing benzene to provide ene-nitrile 82 in 75 % yield. Finally, bromine-mediated aza-Achmatowicz reaction [44] of 82 then delivered oxidopyridinium betaine 83 in 65 % yield. 

Disubstituted tellurins were obtained by reduction (with DIBAL-Fl) of the the 4-oxo-4//-tellurins, prepared by the addition of alkali metal tellurides to... 

Reduction of unsaturated -/-lactones (e.g. 91) has been applied to the synthesis of furanophanes lactonization of (92) followed by reduction with DIBAL gives (93) (70TLli). 

Substituted succinonitriles give 3-substituted pyrroles on reduction with DIBAL-H (84TL1659) via diimine intermediates which undergo cyclization and aromatization (Scheme 39). This reaction was used in the synthesis of unusual pyrroles (e.g. 119) which were used to prepare sterically shielded porphyrins (94AG(E)889). 

Barrett used the reaction at the start of his synthesis of an antibiotic.12 The HWE reaction with the enal 47 gives the diene ester 48 and by reduction with DIBAL, the dienol 49. 

The key intermediate in the total synthesis of furaquinocin was obtained in good yield by a reductive Heck reaction that proceeded with a sterically hindered base pentamethylpiperidine (PMP) <02JA11616>. A new hypothesis for the major skeletal rearrangement (anthraquinone —> xanthone —> coumarin) that occurs in the complex biosynthesis of aflatoxin Bi was proposed. To test this hypothesis, an intermediate 11-hydroxy-O-methylstergmatocystin (HOMST) was synthesized as shown below. The key transformation in this synthesis involved the treatment of an ester-aldehyde with Pr3SiOTf, which smoothly produced a mixed acetal. Direct reduction with DIBAL-H led to the aldehyde. The desired product was eventually obtained via several steps as shown <02JA5294>. 

The ester was cleaved by reduction with DIBAL (Ml AlH) and an achiral version of the normal protecting group put in place. It would obviously be silly to create unnecessary diastereo meric mixtures in these reactions. Then the tin could be exchanged first with lithium and then with an elec-tuophile, even an alkyl halide, with retention of configuration and without loss of enantiomeric purity. The intermediate organolithium compound must have had a stable configuration. 

Af-Acyl-5,5-dimethyloxazolidin-2-one 228 can be considered as a latent aldehyde equivalent. Its reduction with DIBAL-H afforded the corresponding I -hydroxy-alkyloxazolidinone 229 as the sole product. The product can react under the Wadsworth-Homer-Emmons protocol to afford the a-p unsaturated ester 232 or the free aldehyde 231 could be isolated after hydrolysis <030B2001>. This methodology was also employed in the asymmetric synthesis of a-alkyl and p-alkyl aldehydes <03OB2886>. 

Osmium tetroxide-catalyzed dihydroxylation of the chiral a-acetoxysulfones and acetonide formation affords versatile chemical intermediates. Reduction with DIBAL-H provides primary alcohols, and addition of Grignard reagents provides secondary alcohols with excellent stereochemical control of the newly formed chiral center. ... 

There are several ways to cleave the auxiliary from the product 7. Typical reactions include reduction with complex hydrides such as LiBH4 to obtain the alcohol 18 or transamination to the Weinreb amide and subsequent reduction with DIBAL to give the aldehyde 19 that would have been obtained from direct aldol reaction. ... 

Diisobutylaluminum hydride (DIBAL-H) can be obtained commercially neat or in hydrocarbon solvents. Reductions with DIBAL-H must be carried out in the absence of air and moisture. DIBAL-H is a very versatile reagent for the selective reduction of... 

The coupling partner (104) for the aldehyde 86 was synthesized as shown in Scheme 22. Starting with lactone 101 [53], a reduction with DIBAL-H to afford the lactol and extension of the carbon framework furnished compound 102. In six steps, the researchers were able to... 

Isomerizations. A convenient method for the conversion of alkynes to conjugated dienes is by treatment with Ph P. The synthetic application is shown in the preparation of 2,4-alkadienols from 2-alkynoic acids involving esterification with pentafluorophenol, isomerization with PhjP (PhMe, 50°), and reduction with DIBAL-H. Even propargyl bromide can be isomerized to give 1-bromopropadiene, albeit in 29% yield. Conjugated alkadienoic esters and amides are obtained in one step from the pentafluorophenyl alkynoates on reaction with alcohols and amines, respectively, after treatment with catalytic amount of PhjP. 

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