Lithium 1- naphthalenide

A 17-steroidal ketone was deprotonated by LDA to protect it from reduction during a lithium naphthalenide cleavage of a benzyl ether. ... 

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

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... 

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... 

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). 

Diols can also be deoxygenated via Mv-sulfonate esters using sodium naphthalenide.294 Cyclic sulfate esters are also cleanly reduced by lithium naphthalenide.295... 

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>. 

Whitlock et al.14 discovered a reductive cyclization of enediynes promoted by lithium naphthalenide that provides substituted fulvenes and suggested a dianionic mechanism (Scheme 6). However, even now it is still unclear whether the enediyne dianion is indeed the cyclizing species or whether the initially formed acyclic radical-anion cyclizes first to give a fulvene radical-anion which is further reduced by lithium to give the cyclic dianion. 

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). 

Scheme 6 Dianionic cyclization of enediynes promoted by double lithium naphthalenide reduction.

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. 

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