Caibocycles

C. D. Gutsche and D. Redmore, Caibocyclic Ring Expansion Reactions, Academic Press, New York, 1968, p. 111. 

G. Jones, S. P. Stanforth, The Vilsmeier Reaction of Fully Conjugated Caibocycles and Heterocycles, Org. React. 1997, 49, 1-330. 

Secondary amines an easily converted into formamidines reaction with amidines (equation 24). Deprotonation and addition of electrophiles, including alkyl halides, acyl halides, aldehydes and dise-lenides, permit the introduction of various groups adjacent to the amino center, and therefore can be considered as an oxidation. Alkylation with dihalides gives intermediates which lead to new caibocyclic rings after removal of the formamidine group (equation 2S). ... 

Laboratoire des Caibocycles, Umversite de Paris-Sud, 91405 ORSAY, France... 

This type of cyclization has recendy been used in the caibocyclic field to synthesize the tetracyclic glycol (234), an advanced intermediate in the synthesis of the antimicrobial and amoebicidal agent ikaru-gamycin. Thus photocyclization of a 2 1 mixture of trienes (235) and (236) led to a 4 1 mixture of the two possible conrotatory closure products (237) and (238), which likely reflect the conformational bias in the ground state of the (20-triene (23fo and 236b, respectively). ... 

The sixth thrane, caibocycles fixmi carbohydrates, explores how functionalized cy-lopentanes and cyclohexanes can be prepared from carbohydrate precursors, thereby extending the usefulness (rf sugars for the synthesis of mainstream organic compounds. 

S. Hanessian and R. Ldger, Expedient assembly of caibocyclic, heterocyclic, and polycyclic compounds by MCjSn radical mediated carbocyclizations of dienes and trienes A novel oxidative cleavage of the C-Sn bond, J. Am. Chem. Soc. 774 3115 (1992). 

In contrast, the related cyclizations used to form caibocyclic systems have been of limited synthetic value due to the acid sensitive nature of the derived allylic ether product (equation 1 Figure 11). The sensitivity of these caibocycles may be rationalized by considering the poor orbital oveilap between the allylic C—O bond with the adjacent ir-bond in a five-, six- or seven-membered ring. ... 

Attempts to cyclize ethyl ( )-2-acetyl-2-methyl-6-bromo-4-hexenoate have been unsuccessful, with ediyl 2-melhyl-3-oxobutanoate isolated as the major product of die reaction (equation 52). Loss of butadiene, as required for this transformation, is clearly facilitated by the ability of a 3-keto ester stabilized (radical or anion) intermediate to serve as an effective leaving group in the reaction. Thus, cyclization of ( )-8-bromo-4-mediyl-6-octen-3-one proceeds smoothly to provide die expected caibocycle in 91% isolated yield (equation S3). 

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

Scheme 70. The Rh-catalyzed [2 + 2 + 2] caibocyclization of 1,6 enynes with symmetric and unsymmetrically substituted alkynes.

Cermak RC, Vince R. ( ) 4p-Amino-2a,3a-dihydroxv-lp-cyclopemanemethanol hydrochloride. Carbocyclic ribofuranosylacnine for the synthesis of caibocyclic nucleosides. Tetrahedron Lett 1981 22 2331-2332. 

Arita M, Adachi K, Ito Y, Sawai H, Ohno M. Enantioselective synthesis of the caibocyclic nuclemides (-)-aiisteromycin and (-J-neplanocin-A by a chemicoenzytnatic approach. ] Am Chem Soc 1983 105 4049-4055. 

Sicsic S. Ikbal M, Le Gof6c F Otemoeitzyniatk approach to caibocyclic analogues of ribonucleotides and nicotinamide ribose. Tenahedron Lett 1987 28 1887—1888. 

The Diels-Alder reaction, more than 50 years after its discovery (i), is still one of the most efficient methods for the synthesis of caibocycles. A diene and a dienophile react to afford a carbocyclic compound with up to four stereogenic centers, in just one synthetic operation, and with a go control of regio- and stereochemistry (2). On the other hand carbohydrates, I, because of their nature have normally been transformed in polyoxygenated compounds (i). However, the last few years have witnessed an increasing interest in the not so straightforward transformation of carbohydrates into carbocycles (4),... 

The photorearrangement of caibocyclic 2-phenyhhio-l,3-diols to give deoxy-thiosugars is covered in Chapter 12, the qmthesis of l,6-anhydro-2,3,4-trideoxy-3-phenylthk>4>e 3a hrt>-hex-3-enopyranose in Chapter 13, sulfur-containing KDN derivatives in Chtq>ter 16, and a synthesis < heit ddin wMch involves phenyhhio intermediates is referred to in Qiapter 24. 

The same group has also prq >ared 4a-aminocyclopent8ne-lo(,2p,3p-triol as an intermediate in the synthens of caibocyclic nucleosides by way of an intramolecular cycloaddition of a nitrone-alkene derivative. ... 

Overall, the ortho substituted 4-phenoxyquinolines generated in variation A which show activity in the primary screen demonstrate excellent curative control of wheat powdery mildew. Conversely, strong protective control was observed for active materials generated from modification of the quinoline caibocycle and active materials from quinoline heterocyclic ring modification showed little protective or curative control. Unfortunately, when compounds were prepared with curative substituents in the phenolic ring and protectant substituents in the quinoline carbocycle, relatively little wheat powdery mildew activity was observed. 

I 4 Polycyclic Arenes Containing Seven-Membered Caibocycles... 

Chen Z, Zhu J, Xie H, Li S, Wu Y, Gong Y (2010) Palladium catalyzed synthesis of 2-trifluoro-methylquinolines through a domino sonogashira-alkyne caibocyclization process. Chem Commun 46 2145-2147... 

---