Intramolecular RhCl

Motherwell and Whitehead et al. reported a similar intramolecular reductive aldol reaction of aldehyde-enoate derivatives. The cyclization of 6-oxo-ester 23 was catalyzed by RhCl(PPh3)3 (1 mol%) with Et3SiH (210 mol%) as terminal reductant (Scheme 9) [17,18]. The cyclization proceeded at 50 °C for 18 h to give the aldol product 24 in 81% yield with ds-selectivity (cis trans =... 

This alkylation reaction can be applied to intramolecular alkylation affording cyclic products, as shown in Equations (19)-(21). The reaction of 2-vinylpyridines with 1,5- or 1,6-dienes results in the formation of five- or six-membered carbocycles with good efficiency.20,20a,20b In addition to pyridine functionality, oxozole and imidazole rings can be applied to this intramolecular cyclization. When the reaction is conducted in the presence of a monodentate chiral ferrocenylphosphine and [RhCl(coe)2]2, enantiomerically enriched carbocycles are obtained. A similar type of intramolecular cyclization is applied to TV-heterocycles. The microwave irradiation strongly... 

It is possible to carry out the [2+2+2] cyclotrimerization reaction in a regioselective manner by using a partially or completely intramolecular approach. Rhodium-catalyzed intramolecular cyclotrimerization of 1,6,11-triynes, which construct fused 5-6-5 ring-systems, has been studied extensively [33-36]. Cyclization of 1,6,11-triyne 47 catalyzed by RhCl(PPh3)3, gives the tricyclic benzene 48 in good yield (Eq. 14) [33a]. 

Inter- and intramolecular alkyne cyclotrimerizations of 57 catalyzed by RhCl(PPh3)3 af ford substituted carbazoles that are relevant to natural product and drug-related synthe-... 

Rhodium complexes are able to transform various enynes 1 into the corresponding bi-cyclopentenones 2 with equal efficiency to that found with cobalt, and facilitate previously formidable PK reactions. The scope of the substituents on the alkyne for the intramolecular reaction is broad alkyl la/b and aryl-substituted substrates Ic provide the desired products in excellent yield with both [RhCl(CO)2]2 and [RhCl(CO)dppp]2 (Tab. 11.3). 

Auto-tandem hydroformylation-cyclization, catalyzed by [RhCl(cod)]2, enables expansion of the organic skeleton of unsaturated silyl enol ethers (Scheme 10). Linear aldehydes generated in the hydroformylation step subsequently undergo Rh-catalyzed, intramolecular Mukaiyama aldol addition. Bicyclic ketones are also accessible from cyclic silyl enol ethers. 

Intramolecular hydrosilylations of functionalized alkenes followed by hydrogen peroxide oxidation provide powerful methods for organic syntheses86-88. The reactions of allylic O-dimethylsilyl ethers 59 promoted by platinum catalysts, e.g. Karstedt s catalyst and Pt(PPh3)2(CH2=CH2), or rhodium catalysts, e.g. Rh(acac)(COD) and [RhCl(CH2=CH2)2]2> proceed via 5-endo cyclization to give oxasilacyclopentanes 60 with a couple of exceptions in which siloxatanes 61 are formed (Scheme ll)87,89. 

Alkynes are poor dienophiles in the Diels- Alder reaction decomposition occurs by an attempted thermal intramolecular Diels-Alder reaction of dienynes at 160 °C. In contrast, the Ni-catalysed [4+2] cycloaddition of the dienyne 50 proceeded smoothly at room temperature using tri(hexafluoro)isopropyl phosphite to give 51, which was converted to the yohimbine skeleton 52 [15]. The same reaction is catalysed by RhCl(Ph3P)3 in trifluoroethanol [16]. Intramolecular Diels-Alder reactions of the 6,8-dieneyne 53 and the 1,3,8-triene 55, efficiently catalysed by [Rh(dppe)(CH2CH2)2]SbF6 at room temperature, gave 54 and 56 [17],... 

Intramolecular 2 + 2 + 2-cycloisomerizations of cyclic triynes and enediynes have been reported with RhCl(CO)(PPh3)2.126 The transition metal-catalysed rearrangement of alk-5-ynals to /-alkynyl ketones and cyclopent-l-enyl ketones was developed using [Rh(P(OPh)3)2]BF4 or Cu(OTf)2 as a catalyst and the effect of substituents on the partition to products was elaborated (Scheme 84).127... 

Intramolecular olefinic C-H/olefin coupling with the aid of Ru(CO)3(PPh3)2, which is also effective for the reaction of aromatic ketones with olefins, yields the carbocyclic compounds in excellent yield (Eq. 42) [67]. This type of cy-clization reaction can be extended to an asymmetric version when the [RhCl(coe)2]2/PPFOMe catalyst system is employed [68]. 

Acylsilanes serve as acyl donors in the Pd-catalyzed cross-couplings with allyl trifluoroacetates,243 aryl halides,244 and alkenyl halides.2 Intramolecular acylation of alkynes with acylsilanes proceeds under catalysis by [RhCl(CO)2]2.246... 

The analogous RhCl(PMe3)3 complexes react at RT with aliphatic and aromatic aldehydes in a reaction first order in aldehyde and Rh complex to give cis-hydridoacyl complexes , cis-HRh(CORXPMe3)3Cl. When pent-4-enol reacts with RhCl(PMe)3, the acylrhodium(lll) hydride can be isolated. However, it undergoes intramolecular cycliza-tion to cyclopentanone (half life, 1 h at 50°C) . 

Intramolecular coordination of a polar group within the substrate olehnic compound has an activating effect, e.g., in the hydrogenation of 23 in the presence of RhCl(PPh3)3 ... 

Since the Rh-Si bond is so strong, the reaction of Si2H6 with RhCl(PH3)2 giving RhCl(PH3)2(SiH3)2 is very exothermic by 82 kcal/mol at the MP2 level, and this disilyl complex is 16 kcal/mol more stable than HRhCl(PH3)2(Si2H5). KM found the transition state for intramolecular rearrangement between these two products, where Si-H and Si-Si bond interact with the Rh atom in a similar fashion as the two Si-H bonds interact with the Rh atom in the transition state between two HRhCl(PH3)2(SiH3) molecules. 

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