By reductive coupling

Compounds with Tin—Tin Bonds. The most important class of catenated tin compounds is the hexaorganoditins. The ditin compounds are usually prepared by reductive coupling of a triorganotin haUde with sodium in Hquid ammonia ... 

Alkyls with groups that cannot / -eliminate (Me, CH2SiMe3) are more stable than those that can (e.g. ethyls). 7>ans-complexes that cannot eliminate by reductive coupling may /3-eliminate ... 

Scheme 9 Synthesis of enantiopure piperazines by reductive coupling of chiral 2,5-diaza-1,5-dienes...

Lnsymmetrical ptnacols, e.g. (19) can be made by reductive coupling of the mixed carbonyl precurHorH, but the yields are poor as the two dimers are also formed,... 

Calculations have estimated that decomposition of [TIMe] by either disproportionation to T1 and TlMe3 or by reductive coupling to give T1 and C2H6 are thermodynamically favored. See ... 

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. 

Matyjaszewski Krzysztof, Dorota Gresta, Hrkach Jeffrey S, Hwan Kyu Kim (1995) Sono-chemical synthesis of polysilylenes by reductive coupling of disubstituted dichlorosilanes with alkali metals. Macromolecules 28 59-72... 

Vitamin B12 derivatives are also effective catalysts for the electroreductive cyclization of bromoalkenes in conductive microemulsions,299 300 or for ring-expansion reactions in cyclic a-(bromomethyl)-(3-keto esters in DMF.301 Vitamin Bi2 attached to an epoxy-polymer has been used in electrosynthesis of valeronitrile by reductive coupling of iodoethane and acrylonitrile.302... 

This reaction has been extensively studied " and I discuss it here merely to point out certain pitfalls. The conversion of a Ni(0) bis (butadiene) cranplex XIX to a Ni(II) bis- r-allylic complex XX (the structures are drawn withmit stereochemical implication) by reductive coupling appears at first sight to be an allowed process each ligand contributes four electrons and the metal contributes two, making ten in all. Thus Eq. (1) is satisfied, provided the metal itself introduces no discontinuity ... 

The preparation of -carotene [j8,/3-carotene (63)] in 50% yield by reductive coupling of retinaldehyde (67) with TiCl4-LiAlH4 has been described. Similarly )3-ionone (68) gives the symmetrical olefin (69). The enolic /3-diketone caro-... 

Interestingly, an attempt to produce the trimer (BNMe2)s by reductive coupling of monoboron and diboron fragments generated (in very low yield) a colourless compound 9.3 that had the molecular mass of the hexamer... 

A fascinating bicyclic compound 10.29, in which two five-membered Sis rings share a common Si=Si double bond, is obtained by reductive coupling of a 1,1-dichlorocyclotetrasilane [eqn (10.21)]. ... 

In similar fashions, the core pathway up to C25 compounds (five isoprene units) is formed by sequential addition of C5 moieties derived from IPP to a starter unit derived from DMAPP. Thus, sesquiterpenes are formed form the precursor 2E, hS-farnesyl pyrophosphate (FPP), and diterpenes from 2E, 6E, IO -geranylgeranyl pyrophosphate (GGPP). The parents of triterpenes and tetraterpenes are formed by reductive coupling of two FPPs or GGPPs, respectively. Rubbers and other polyisoprenoids are produced from repeated additions of C5 units to the starter unit GGPP. 

Dihydrothiophenes. These thiophenes are available by reductive coupling of diketo sulfides. 

Tb(Mes)Si=Si(Mes)Tb (Mes = mesityl) by reductive coupling of Tb(Mes)SiBr2 with lithium naphthalenide262. 

Another class of extended porphycene, containing an extra sp2 hybridized link between 2 and 2 positions of the bipyrrole subunit has been synthesized by hydrogenation of 80 resulting in the formation of 22jt-electron conjugated porphycene homologue 87 (Scheme 38), also synthesized from pyrrole dialdehyde 86 by reductive coupling under McMurry conditions. 

Tetrasilapentanes 4, R = Pr or neo-pentyl, were synthesized by reductive coupling of the linear 1,5-dichloro-l,2,4,5-tetrasilapentane with lithium biphenyl in 77-87% yields <2002EJI1772>. 

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