With lithium naphthalenide

Very recently, the first disulfur complexes of a tetracoordinated transition metal PtS2[P(Ar)Me2]2 (Ar=Tbt, Bbt) were synthesized by the reaction of ze-rovalent platinum complexes Pt[P(Ar)Me2]2> generated by treatment of the dichloride complexes PtCl2[P(Ar)Me2]2 with lithium naphthalenide, with elemental sulfur (Scheme 6) [37]. Since the use of excess elemental sulfur also... 

The allylic alkylation products represent useful synthons, as exemplified by the reaction sequence outlined in Scheme 10.4. For example, reductive ozonolysis of the allylic alkylation product 15 afforded the y-lactone 16 as a single diastereoisomer. Sequential alkylation with methyl iodide, and reductive alkylation using lithium naphthalenide with allyl iodide furnished the ternary-quaternary substituted y-lactones 17a/17b in 72% overall yield, as a 10 1 mixture of diastereomers favoring 17a [18]. This method provides a versatile approach to the construction of a variety of a-quaternary-/9-ternary stereogenic centers. 

A bicyclo[2.2.0]hexan-l-ylmethyl phosphate was reduced by lithium naphthalenide with cleavage of the central bicyclic bond to give a methylenecyclohexane.106... 

Thus, the intramolecular reductive cyclization of diethynylsilane, followed by quenching with the remaining lithium naphthalenide with a bulky chlorosilane and transmetalation with ZnCl2(tmen) (tmen = MAf.JVW -tetramethylethylenediamine), affords 2,5-dizinc silole 5, which is subsequently treated with the appropriate aryl bromides in the presence of a Pd catalyst to give the corresponding 2,5-diarylsiloles 6 in high yields. 

Cyclohexenyl-, (l-cyclohexenylmethyl)lithium and others are prepared in good yields from sulfides with lithium naphthalenide or lithium 1-(dimcthylamino)naphthalenide32. 

A variation of this transfonnation reacts the acid with hthium naphthalenide in the presence of 1-chlorobutane. The product is the ketone. A related reaction treats the lithium carboxylate with lithium metal and the alkyl halide, with sonication, to give the ketone. ... 

R R M were prepared by reduction of the dibromides R R MBr2 with lithium naphthalenide (method A), by thermolysis of a disilene (method B), and the ligand exchange of divalent group 14 element species (method C). In all cases except for the synthesis of Tip2PbS4, exclusively tetrasulfides R R MS4... 

For example, precursor (S)-57 may be prepared by reaction of R)-56 with methyllithium or by reduction of (S)-56 with lithium naphthalenide and subsequent methylation with iodomethane, making the overall transformation of the diastereomeric mixture 56 nearly quantitatively (Scheme 6) [87]. 

Another germaallene was also reported in 1998 by Okazaki et al. Initially, the report of a germaallene trap with chalcogens, alkylidenetelluragermirane 86a, appeared in 1997. The germylene precursor 82 is made in situ from dichloroger-mane 81 and two equivalents of lithium naphthalenide (Scheme 23). The addition... 

Beau and Sinay described a method which laid the groundwork for cyanohydrin acetonide alkylations [1]. Their strategy involved alkylation and reductive desulfonylation of glucopyranosyl sulfones 4. In this one-pot procedure, low temperature alkylation and subsequent reductive desulfonylation with lithium naphthalenide generated -C-glycosides with good selectivity >10 1 j3 a) and in moderate to good yield (Eq. 1). 

Alkenylsilanes can be prepared from aldehydes and ketones using lithio(chloromethyl)trimethylsilane. The adducts are subjected to a reductive elimination by lithium naphthalenide. This procedure is stereoselective for the E-isomer with both alkyl and aryl aldehydes.82... 

Attempts to form cyclotrigermanes (and, subsequently, digermenes see Section II.B.l) from the reductive cyclization of diaryldichlorogermanes and lithium naphthalenide (LiNp) with particularly bulky substituents on the aryl groups (i.e., isopropyl) led, instead, directly to the tetraaryldiger-menes by reductive coupling. 

A similar strategy can also be used in a seven-step procedure of preparation of 3/3,25-dihydroxy-cholesta-5,7-diene from ergosterol giving a total yield of 30%. The 3-hydroxy function of ergosterol is protected as /-butyldimethylsilyl ether before the 5,7-diene system is treated with l,4-dihydrophthalazine-l,4-dione. In this case, the key step is a very mild method for the cleavage of the hetero Diels-Alder adduct using lithium naphthalenide <1999S1331>. 

Aromaticity of the products is only one of the factors accounting for the efficiency of these cyclizations as evidenced by the discovery of a dianionic synthesis of nonaromatic 5-membered heterocycles by Tamao and coworkers who found that reduction of bis(phenylethynyl)dialkylsilanes with lithium naphthalenide resulted in formation of a cyclized product by endo-endo cyclization15 (Scheme 7). 

Preparation from activated Cb(O).1 An activated Cu, prepared by lithium naphthalenide reduction of CuIPBu3 (12,140), reacts with primary alkyl bromides at -50 to -78° to form alkylcopper reagents that undergo 1,4-addition to cyclo-hexenone in moderate to high yield. This conjugate addition is facilitated by ClSi(CH3)3 and a phosphine. 

Four new stable digermenes 66-69 were synthesized from dichlorogermanes and sodium in toluene or lithium naphthalenide (Scheme 10). 66 and 68 have been characterized by X-ray61 (see Section III,B,1). 66-6851 keep their digermene structure in solution, in contrast to 6960 (probably the E isomer due to the steric hindrance in the Z isomer), for which an interconversion with the corresponding germylene was observed. 

Highly reactive calcium can be readily prepared by the reduction of calcium halides in tetrahydrofuran solution with preformed lithium biphenylide under an argon atmosphere at room temperature.5 This colored calcium species seems to be reasonably soluble in THF. However, the reactive calcium complex prepared from preformed lithium naphthalenide was insoluble in THF solution and precipitated out of solution to give a highly reactive black solid. The exact nature of this black calcium complex has not been determined. Acid hydrolysis of the black material releases naphthalene as well as THF. Accordingly, the most likely structure of the black material is a Ca-naphthalene-THF complex similar in nature to the soluble magnesium-anthracene complex recently reported.6... 

FIGURE 17a. Alternative routes for vinylogous birch reductive cleavage of cinnamyl ether promoted by lithium naphthalenide. Reprinted with permission from Reference 22. Copyright 1996 American Chemical Society... 

The synthesis of oxygen- and nitrogen-containing heterocyclic compounds by anionic cyclization of unsaturated organolithium compounds has been reviewed recently. " Broka and Shen reported the first intramolecular reaction of an unstabilized a-amino-organolithium compound using reductive lithiation of an A,5-acetal derived from a homoaUylic secondary amine (Scheme 21). Just one example was reported treatment with lithium naphthalenide gave the pyrrolidine product, predominantly as the cis isomer. 

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