Super-hydride reduction with

Sulfones are useful organosulfur compounds.328 jn Pickett s synthesis of 9-methylgermacrene-B, sulfone 318 was treated with n-butyllithium to generate the a-carbanion.229 Alkylation with the allylic chloride shown gave 319.330 Hydrolysis of the acetate to an alcohol was followed by treatment with a palladium catalyzed Super-Hydride reduction of the sulfone to give 320 in 82% yield. Alternatively, sodium amalgam and Raney nickel [Ni(R)] can be used to remove sulfur from organic molecules (sec. 4.9.D). 331... 

A simple and general method for the preparation of surfactant-free, thiol-functionalized iridium nanoparticles was reported by Ulman and coworkers in 1999 [11], The synthesis consisted of a reduction of the dihydrogen hexachloroiri-date (IV) H2lrCl6 H20 precursor by lithium triethylborohydride ( super-hydride ) in the presence of octadecanethiol (C18H37SH) in tetrahydrofuran (THF) (Scheme 15.1). The obtained iridium nanoparticles were crystaUine with fee (face-centered cubic) packing, and showed a wider size distribution with diameters ranging from 2.25 to 4.25 nm. 

N-Methylation of 3 and reduction of the crystalline oxazolidinone 4 with lithium aluminum hydride was found to give a superior yield of DAIB (5) and a more easily purified product than exhaustive methylation of 2 with methyl iodide and reduction of the quaternary methiodide with Super-Hydride. Recently, a modified version of DAIB, 3-exo-morpholinoisoborneol MIB), was prepared by Nugent that is crystalline and that is reported to give alcohols in high enantiomeric excess from the reaction of diethylzinc with aldehydes. ... 

Lithium triethylborohydride (Super-Hydride) is a much more powerful reducing agent than lithium aluminium hydride. It is useful for the reductive dehalogenation of alkyl halides, but unlike lithium aluminium hydride does not affect aryl halides. It is available as solution in tetrahydrofuran in sealed containers under nitrogen. The solutions are flammable and moisture sensitive and should be handled with the same precautions as are taken with other organometallic reagents (see Section 4.2.47, p. 442). 

Red-Al [sodium bis(2-methoxyethoxy)aluminium hydride] reduces aliphatic halides and aromatic halides to hydrocarbons. Reductive dehalogenation of alkyl halides is most commonly carried out with super hydride. Epoxide ring can also be opened by super hydride. 

Boranes are generally less electron rich than corresponding aluminium analogues and electron transfer mechanisms are usually not considered for reduction reactions. However, an increase of the hydridic character in complex hydrides such as.LiBEt3H ( super hydride ) [68] or LiAlH4 [66] allows for the formation of well-characterized radical products in reactions with unsaturated acceptor heterocycles such as (3). Electron transfer mechanisms for the reduction by complex hydrides should be quite intricate because the coordinatively saturated donor moiety (MHn ) and the a acceptor part (e.g. Li" ) can now well separately interact with the coordinating n acceptor substrate. 

Newkome et al. used nucleophilic aromatic substitution to incorporate the 2,6-pyrido unit into a triazamacrocycle which was precursor to a series of cryptands (Scheme 11) <81TL3039>. The sequence uses a tertiary aminoalcohol as the nucleophile in a sodium hydride-mediated reaction with 2,6-dichloropyridine. In the second step, the tertiary amines function as nucleophiles in a reaction of triethylene glycol diiodide. The tertiary amines are converted into quaternary ammonium salts in the process. The system must be demethylated to form the neutral crown but conditions must be such that reduction of the pyridine residue does not occur. This was accomplished by using the commercial reagents L-Selectride and Super-Hydride. 

Chloroborepin (17) is readily converted to the corresponding Mo(CO)3 complex (Equation (4)) by reaction with tricarbonyl-tris(pyridine)molybdenum and BF3 Et20 in ether. This Mo(CO)3 derivative is smoothly converted to the corresponding 1 /f-borepin-molybdenum complex (18) by reduction with lithium triethylborohydride (Super-Hydride) in THF (Equation (5)). This is noteworthy as (18) cannot be prepared directly from the highly labile 1//-borepin itself <93AG(E)1065>. 

Reduction of a, -unsaturated carbonyl compounds (6, 491 492). The final paper has now been published. In general, )3-5ubstituted cyclohexenones undergo exclusive 1,4-reduction with either Selectride. Acyclic enones generally undergo 1,2-reduction to allylic alcohols. The Selectrides are particularly useful for 1,4-reduction of enoates. Super-Hydride (lithium triethylborohydride) is less useful for this purpose. Unfortunately L-Selectride reduces o./S-acetylenic esters only to propargylic alcohols. 

Both Parsons [49] and Mulzer [50, 51] used related Eschenmoser-Claisen rearrangements to set a benzylic quaternary stereocenter in their approach to morphine alkaloids (Scheme 7.25) [5, 52, 53]. Reduction of cyclohexenone 65 followed by Eschenmoser-Claisen rearrangement gave unsaturated amide 66, which was subsequently converted into a known precursor of morphine (Scheme 7.24, Eq. 1). Treatment of the acid sensitive phenanthrenol 67 with dimethylacetamide dimethyl acetal (4) afforded amide 68 comprising the entire carbon skeleton of the morphine (Eq. 2). The amide was subsequently reduced to a primary alcohol (69) using lithium triethylborohydride (Super-Hydride), the most suited reagent to perform this task. Previous total syntheses of the alkaloid were intercepted at the stage of dehydrocodeinone. 

Figure 4 shows another analogous synthetic scheme. Selective ditosy-lation of [2] and subsequent reduction with super hydride yielded dide-oxygenated derivatives [7] and An anhydro disaccharide derivative [9] was also prepared via glycosidation of an intermediate with a galactose derivative. 

Because they possess an odd number of valence electrons the elements of this group can only satisfy the 18-electron rule in their carbonyls if M-M bonds are present. In accord with this, mononuclear carbonyls are not formed. Instead [M2(CO)s], [M4(CO)i2] and [M6(CO)i6] are the principal binary carbonyls of these elements. But reduction of [Co2(CO)g] with, for instance, sodium amalgam in benzene yields the monomeric and tetrahedral, 18-electron ion, [Co(CO)4] , acidification of which gives the pale yellow hydride, [HCo(CO)4]. Reductions employing Na metal in liquid NH3 yield the super-reduced [M(CO)3] (M = Co, Rh, Ir) containing these elements in their lowest formal oxidation state. 

---