Synthesis of carbocycles

Intramolecular hydroarylation of 5-aryl-1-pentynes with catalytic amounts of transition-metal chlorides, such as PtCh and [RuCl2(CO)3]2, at 80 °C in toluene 

Transition-Metal-Mediated Aromatic Ring Construction, First Edition. Edited by Ken Tanaka. 2013 John Wiley Sons, Inc. Published 2013 by John Wiley Sons, Inc. 

The Gads-catalyzed reaction was improved by the site selectivity and scope of the substrate in the intramolecular hydroarylation of some 5-aryl-1-pentynes 

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Trost and co-workers have explored asymmetric transidon metal-catalyzed allylic alkyla-dons. Details on this subject have been well reviewed by Trost and others. With the use of asymmetric palladium-catalyzed desymmetrizadon of meso-2-ene-l,4-diols, cii -l,4-dibenzoy-loxy-2-cyclopentene can be converted to the enandometrically pure cii -4-rfirr-butoxycar-bamoyl-l-methoxycarbonyl-2-cyclopentene. The product is a usefid and general building block for synthesis of carbocyclic analogs of nucleosides as presented in Scheme 5.12. 

In contrast to the synthesis of carbocyclic rings, the Cope rearrangement has been used sparsely for generating azepinones. Recently, the enantioselectivity of the conversion of 2-aza-divinylcyclopropane 286 has been investigated. The synthesis started from the optically active cyclopropanecarboxylic acid (90% ee), which had been converted into the isocyanate 286 by initial azidation to 285 and a consecutive Curtius rearrangement. Furthermore, the conditions of the iso-... 

Another versatile domino process for the synthesis of carbocycles as well as heterocycles is the Pd-catalyzed reaction of organic halides or triflates with alkynes or allenes, which contain a carbo- or heteronucleophile in close vicinity to these functionalities (see Scheme 6/1.75) [133]. 

Cu-catalyzed domino reactions have been used for the synthesis of carbocycles, as well as for heterocycles such as indoles, benzoxazoles, and quinoxalines. A very useful process is also the combination of the formation of allyl vinyl ethers, followed by a Claisen rearrangement. 

Miller and coworker report a total synthesis of carbocyclic polyoxin C from cis-(N-tert-butylcarbamoyl)cyclopent-2-en-l-ol, as shown in Scheme 5.11.89 This synthesis features a... 

Feringa and co-workers described the tandem addition-aldol cyclization protocol leading to the formation of 6,6-, 6,7-, and 6,8-annulated bicyclic systems (Scheme 68).39 Using Cu(n)-29 as catalyst and functionalized organozinc reagents as nucleophiles, the conjugate addition reaction followed by aldol cyclization can offer highly enantioselec-tive annulation products (up to 98% ee). This method can be used in the synthesis of carbocyclic compounds, such as steroids, terpenes, and other natural products. 

Abstract In this chapter different types of domino-processes are described which consist of the combination of cationic, anionic, radical, pericyclic and transition metal-catalyzed as well other reactions. The methodology is used for the highly effective synthesis of carbocycles and heterocycles as well as of natural products and other interesting materials. It is also employed as an efficient tool in combinatorial chemistry. 

Transition-metal-promoted cycloaddition is of much interest as a powerful tool for synthesis of carbocyclic stmcture in a single step. Utilization of carbon monoxide as a component of the cycloaddition reaction is now widely known as the Pauson-Khand reaction, which results in cyclopentenone formation starting from an alkyne, an alkene, and carbon monoxide mediated by cobalt catalyst. Although mechanistic understanding is limited, a commonly accepted mechanism is shown in Scheme 4.16. Formation of dicobalt-alkyne complex followed by alkene... 

The ciT-substituted cyclobutane ester 502 is of interest as intermediate for the synthesis of carbocyclic 503 (equation 218). Ring opening of the bicyclic (-l-)-Nopinone 501... 

A cyclic ring sulfite (with an -O-SO-0- ring in a carbocyclic nucleoside) was oxidised by RuClj/aq. Na(lO )/CCl -CH3CN/0°C as a synthon for the convergent synthesis of carbocyclic nucleosides (Fig. 5.17) [116]. 

In conjunction with this, Jeong reported the cycloadditions of bis(allyl) and bis(homoallyl) acetals of alkynals leading to bicyclic lactols. Smaltz extended its utility to the synthesis of carbocyclic nucleoside by coupling with nucleophilic substitution of a 7r-allylic palladium complex (Equation (46)). ... 

Chiral cyclobutanes can be prepared by cycloaddition of alkenes substituted with one or more chiral auxiliary groups. A diastereofacial selectivity of 95% was observed in the diethylalu-minum chloride catalyzed cycloaddition of 1,1-dimethoxyethene (36) with ( — )-dimenlhyl-3-yl fumarate (37).16 The chiral cyclobutane 38 has been used as an intermediate in the synthesis of carbocyclic oxetanocin analogs. 

Synthesis of Carbocyclic and Heterocyclic 7r-Electron Systems with Pentafulvenoid Chloroformamidinium Chlorides K. Hafner and H.-P. Krimmer, Angew. Chem., Int. Ed. Engl., 1980,19, 199-201. 

Review coverage of the chemistry involved in the synthesis of enantiomerically pure natural products from carbohydrates is now extensive [2]. It is relevant to note that whereas, in 1983, the numbers of carbocyclic target compounds were relatively limited, as outlined in an authoritative monograph written by Hanessian [3], a comprehensive review of the methods available for making cyclopentane and cyclohexane derivatives from carbohydrates published 10 years later [4] cited 338 references, more than 80% of which were dated 1980 or later. The attention afforded the synthesis of carbocyclic products also features prominently iu a 1993 review of the use of sugars in the preparation of enantiomerically pure natural products [2],... 

Dimerization-double silylation has been extended to the synthesis of carbocycles from bis-diene substrates. Pd(dba)2 is used to catalyze the regioselective reaction at room temperature, yielding carbocycles with al-lylic silane side chains [Eq. (12)].53... 

Cycloaddition reactions are valuable for the synthesis of carbocyclic compounds. Each of the following compounds can be formed by either a [4 + 2] or [2 + 2] cycloaddition as a last step in the synthesis. Draw the structures of the reagents you think would undergo cycloaddition to give the compounds shown. 

Review Syn 383 (1974) (Synthesis of Carbocyclic Spiro Compounds via Intramolecular Alkylation Routes)... 

Scheme 15. Enantioselective synthesis of carbocyclic tertiary ethers and spirocycles through Mo-catalyzed asymmetric olefin metathesis...

Lewis acid catalyzed intramolecular coupling of allylsilanes with aziridines serves as a useful route for the synthesis of carbocycles having the y-amino olefin unit 104 (equation 80)149. However, this reaction does not occur in an intermolecular manner. 

Cycloaddition to a-P-unsaturated carbonyl systems represented by different carbohydrate enones yield annulated osides. These bicyclic molecules are used for synthesis of carbocyclic systems using the stereochemical information issued from sugar... 

Diaryliodonium fluorides can be used as efficient reagents for the arylation of silyl enol ethers [71, 72]. The reaction of silyl enol ethers 95 with o-nitro-phenyliodonium fluoride 96 results in a regiospecific arylation yielding arylke-tones 97 in good yields (Scheme 43) [72]. This arylation has been applied in a new, regiocontrolled synthesis of carbocycle-fused indoles [72]. 

Chapter 9 describes various methods for the synthesis of carbocyclic systems. The preparation of such systems can be achieved either by connecting two atoms within a single molecule (intramolecular reaction) or joining together two separate molecules (intermolecular reaction). 

Problem 1 focuses on reagents for the synthesis of carbocyclic systems. Problems 2-4 address selectivity issues associated with carbocyclic systems. The syntheses of TMs in Problems 5 and 6 require the selection of specific reagents to achieve chemo-, stereo-, or enantioselective cyclizations. 

Chapters 30-37 are concerned with the synthesis of carbocyclic rings. The disconnections are therefore of C-C rather than C-X bonds and the choice is correspondingly greater. We start in this chapter with three-membered rings and work our way upwards to six-membered. But the principles, particularly of cyclisation, remain the same as in chapter 29. 

N. Sotomayor, E. Lete, Aryl and Heteroaryllithium Compounds by Metal-Halogen Exchange. Synthesis of Carbocyclic and Heterocyclic Systems, Curr. Org. Chem. 2003, 7, 275-300. 

In 1988 Koizumi et al. reported the first sulfoxide used as a chiral synthetic equivalent of dimethyl acetylene dicarboxylate [86a]. The synthesis of dimethyl (R)s-2-(10-isobornylsulfmyl) maleate (88), its reaction with cyclopentadiene catalyzed by ZnCl2, and the further transformation of the major adduct 89 into a half-ester 90 (which had been used as the starting material for the synthesis of carbocyclic nucleosides (-)-aristeromycin and (-)-neplanomicin) are described (Scheme 46). 

Martinez, L.E. et al. Highly Efficient and Enantioselective Synthesis of Carbocyclic Nucleoside Analogs Using Selective Early Transition Metal Catalysis. 2.4 1996 [148]... 

Matsugi, M. et al. Highly Stereoselective Synthesis of Carbocycles via a Radical Addition Reaction Using 2,2 -Azobis(2,4-dimethyl-4-methoxyvaleronitrile) [V-70LJ. 2.1 1999 [149]... 

Diaryliodonium fluorides (Ar2IF) are effective reagents in arylation of silyl enolates.330 They have been used for the regiocontrolled synthesis of carbocycle-fused indoles (Scheme 26).331 Ph4BiF also serves for efficient regioselec-tive cr-phenylation of carbonyl compounds via silyl enolates.332 This approach can be extended to cr-alkenylation of carbonyl compounds. 

An interesting application of a chiral nitroso dienophile combined with the conversion of the primarily generated 1,2-oxazine into a cyclopentene derivative has been carried out by Miller et al. and is directed towards the synthesis of carbocyclic nucleoside analoga such as 4-28 [353 -355]. The alanine derived dienophile 4-23 cycloadded to cyclopentadiene giving two diastereomeric, however easily separable adducts 4-24 and 4-25. The N-0 bond of 4-24 was then reduc-... 

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