DIBAL diisobutylaluminum

The conversion of carboxylic acid derivatives (halides, esters and lactones, tertiary amides and lactams, nitriles) into aldehydes can be achieved with bulky aluminum hydrides (e.g. DIBAL = diisobutylaluminum hydride, lithium trialkoxyalanates). Simple addition of three equivalents of an alcohol to LiAlH, in THF solution produces those deactivated and selective reagents, e.g. lithium triisopropoxyalanate, LiAlH(OPr )j (J. Malek, 1972). 

DIBAL Diisobutylaluminum hydride DMAP 4-(dimethylamino)pyridine DME 1,2-dimethoxyethane... 

DIBAL diisobutylaluminum hydride LD50 dose that is lethal to 50% of test subjects... 

Abbreviations Ac, acetyl AIBN, 2,2 -azobisisobutyronitrile All, allyl Alloc, allyloxycarbonyl Bn, benzyl BOM, benzyloxymethyl BPC, p-phenylbenzoyl Bu, butyl t-Bu, tert-butyl Bz, benzoyl CAN, ammonium hexanitratocerate (IV) Cbz, bezyloxycarbonyl CDl, carbonyldiimizazole ClAc, chloroacetyl Cp, cyclopentadienyl CSA, DL-lO-camphorsulfonic acid DABCO, l,4-diazabicyclo[2.2.2]octane DAST, diethylaminosulfur trifluoride dba, dibenzylideneacetone DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, iV,iV-dicyclohexylcarbodiimide DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoqui-none DEAD, diethyl azodicarboxylate DEIPS, diethylisopropylsilyl DIBAL, diisobutylaluminum hydride DMAP,... 

The following abbreviations are used throughout this section Et, ethyl Pr, u-propyl unless otherwise indexed Bu, n-butyl unless otherwise indexed C H2 +1, n-alkyl unless otherwise indexed Bn, PhCH2 Ph, phenyl Ar, aryl Cp, / -cyclopentadienyl, unless otherwise indexed n-, normal iso s-, secondary t-, tertiary c-, cyclo p-, para m-hapto THE, tetrahydrofuran 2,5-DMTHF, 2,5-dimethyltetrahydrofuran TBS, r-BuMe2Si MEM, methoxyethoxymethyl Tf, CF3SO2- acac, acetylacetonate Dibal, diisobutylaluminum hydride. Quite recently, a report on this mechanism of titanium-catalyzed hydromagnesa-tion of acetylenes appeared [120]. 

The BPS group is more stable toward acidic hydrolysis than TBS or the TIPS groups. It survives DIBAL (diisobutylaluminum hydride) reductions, cleavage of THP with aqueous AcOH, and cleavage of isopropylidene and benzylidene acetals with aqueous CF3CO2H. BPS-Cl has been used to selectively protect primary OH groups in inositol (hexahydroxycyclohexane). ... 

Scheme 11 Syntheses of phosphonium dimers and a-phosphinoacetaldehyde diethyl acetals (DIBAL = diisobutylaluminum hydride)...

A significant modification of the Bradsher method was introduced recently by Castle to effect homoannulation of structurally appropriate methyl derivatives of condensed thiophenes in four steps (Scheme 28a, where NBS = N-bromosuccinimide DIBAL = diisobutylaluminum hydride).658 106a l26a The main feature is the conversion of a methyl substituent to the—CH=CH— unit of a peri-condensed ring structure. Yields reported for the steps in the transformation 358c -> 76 are 76, 72%, and 32% (last two steps). The intermediate aldehyde 358d undergoes cyclization at C-l. In the same manner, overall yields of 6% for 34a, 9% for 77, and 27% for 79 were obtained. 

Scheme 2.5 Synthesis of PD 113,271 from L-tartaric acid and D-galactose. (DIBAL, diisobutylaluminum hydride MPM, p-methoxybenzyl TPS, tert-butyidiphenylsilyl and TES,...

---