Tenon

At a me thoxybu tenon e-aniline ratio of 1 2, dianyl is formed and further undergoes cyclization with elimination of the aniline to give 2-methylquinoline (229) in 20% yield (60MI1). 

Zapfen, m. peg, pin, plug, stud, pivot tap, spigot, bung journal, trunnion tenon cone,... 

An interesting consequence of the base-catalyzed isomerization of unsatu-rated ketones described in Problem 22.37 is that 2-substituted 2-cyclopen tenones can be interconverted with 5-sub tituted 2-cyclopentenones. Propose a mechanism for this isomerization. 

Addition of racemic allylic sulfoxide anions to 2(5//)-furanone gives y-1,4-addition adducts1. The simple and induced diastereoselectivities are completely analogous to that of 2-cyclopen-tenone described earlier. 

It is gratifying that the same model holds for the conformationally more flexible cyclohep-tenones. Again, the 4-methyl-2-cycloheptenone led preferentially to the s-compound in the (2-propenyl)siIane addition, based on stereoelectronic grounds. 

The titanium(IV) chloride catalyzed addition of silylenol ethers to 2-substituted cyclopen-tenones stereoselectively yields tnmv-cyclopcntanoncs45 4h. 

A similar trend was observed in the reaction of tri- and tetrasubstituted etiolates derived from 2-unsubstituted or 2-bromo substituted 3,4-dihydro-6-methoxy-1(2//)-naphthalenone16. The trisubstituted cnolate underwent addition to (—)-(2 )-2-(4-methylphenylsulfinyl)-2-cyclopen-tenone via attack on the nonchelated conformation to give an adduct of d.r. [(2S)/(2/ )] 77 23. The tetrasubstituted enolate underwent addition to the corresponding ( + )-(5)-enone via attack on the chelated conformation to give an adduct with the same absolute configuration at C-2 but with d.r. [(2R) (2S)] 95.5-97 4.5-3. 

This type of asymmetric conjugate addition of allylic sulfinyl carbanions to cyclopen-tenones has been applied successfully to total synthesis of some natural products. For example, enantiomerically pure (+ )-hirsutene (29) is prepared (via 28) using as a key step conjugate addition of an allylic sulfinyl carbanion to 2-methyl-2-cyclopentenone (equation 28)65, and (+ )-pentalene (31) is prepared using as a key step kinetically controlled conjugate addition of racemic crotyl sulfinyl carbanion to enantiomerically pure cyclopentenone 30 (equation 29) this kinetic resolution of the crotyl sulfoxide is followed by several chemical transformations leading to (+ )-pentalene (31)68. 

The reaction of 1,3-diamino-1,3-dienes with aryl or a,/J-disubstituted alkenylcarbene complexes leads to the formation of formal [4S+1C] cyclopen-tenones [25a] (Scheme 35). In the case of alkenylcarbene complexes, the substitution of the double bond of the complex in both a- and /J-carbons seems to play a fundamental role as reactions performed in the same conditions but using alkenylcarbene complexes with other substitution patterns leads to compounds of a different nature ([4+3], [4+2] and [2+1] cycloadducts). 

In his first independent work, Helferich prepared y-hydroxyvaleral-dehyde (4-hydroxypentanal) by reduction and ozonolysis of methylhep-tenone, readily available from citral by a retro-aldol reaction. He was able to show that, similarly to the saccharides, this hydroxyaldehyde exists in... 

In-depth discussions of the anatomy of the eye and adnexa have been adequately covered elsewhere in the pharmaceutical literature [13-17] and in recent texts on ocular anatomy. Here a brief overview is presented of the critical anatomical features that influence the nature and administration of ophthalmic preparations. In this discussion, consideration will be given primarily to drugs applied topically, that is, onto the cornea or conjunctiva or into the palpebral fornices. Increasingly, drugs are being developed for administration by parenteral-type dosage forms subconjunctivally, into the anterior and posterior chambers, the vitreous chamber, Tenon s capsule, or by retrobulbar injection. 

As described previously, the Co-mediated carbonylahve Co-cydization of an alkyne and an alkene, is a very powerful procedure in the preparation of cyclopen-tenones [268], However, depending on the reaction conditions it also allows the preparation of 1,3-dienes, which may be intercepted by a Diels-Alder reaction, as described by Carretero and coworkers [285]. As expected, reaction of 6/4-28 with Co2(CO)8 in refluxing acetonitrile led exclusively to the diastereomeric cyclopen-tenones 6/4-29 and 6/4-30 as a 59 41 mixture. However, using trimethylamine-N-... 

A very new example for the combination of an Au -catalyzed [3,3]-rearrangement and a Nazarov reaction has been disclosed by Zhang and coworker. Thus, cyclopen-tenones could be easily achieved by converting en-ynyl acetates in the presence of AuCl(PPh3)/AgSbF6 [320]. 

The Pauson-Khand reaction (PKR) [96] consists of the synthesis of cyclopen-tenones by reaction of an alkene with a dicobalthexacarbonyl complexed alkyne (Scheme 57) and has recently emerged as one of the methods of choice for the obtainment of five-membered carbocyclic rings [97]. Its unique atom connectivity, which involves the two unsaturated carbons of the reagents and the carbon atom of a carbon monoxide ligand of cobalt usually in a regioselective manner (Scheme 57), has brought to refer to PKR as a [2 -I- 2 + 1] cycloaddition. 

Vinylallenes can also be cydized oxidatively. Vinylallene 61 when treated with vanadyl acetonacetonate and tert-butyl hydroperoxide in benzene produced cyclopen-tenone 63, the immediate precursor of methylenomytin B (cf. 5, Eq. 13.1), in 50%... 

It should be noted that upon reaction with an electron-rich cyclobutenone (R1 = R3 = H, R2 = OEt), the major product formed was a cobaltacyclopen-tenone, which may also be considered to be an 772-vinylketene complex. A similar restructure was isolated after heating 114.a with a large excess of triphenylphosphine, which replaces the ligand site vacated by the central C2 unit. Interestingly, such 772-vinylketene complexes are the expected products from the analogous insertion of rhodium into cyclobutenones (e.g., 7). 

Co2(CO)6 fragments at the C=C triple bonds further from the Pt center. The Pauson-Khand reaction between tra 5-Pt C=CC2H[Co2(CO)6] (PR3)2 (R = Et, Bu) (197) and norbomene or cyclopentene gives the corresponding cyclopen-tenones 198 (Scheme 44). ... 

This strategy culminated in the synthesis of the racemic tricycle 282 as a pair of diastereomers that were separated by chromatography. The cyclopen-tenone 274 served as A-ring building block and the C-ring was synthesized utilizing a Diels-Alder reaction between 279 and 280 as the key step. 

Keywords Alkynylcyclopropanes, Propadienylcyclopropanes, Octacarbonyldicobalt, Cyclopen-tenones, Hydroquinones... 

Systematic phase 2 human treatment will start early September 1982 in Reims (Institut Jean-Godinot), in Paris (Hopital Tenon, Hopital St Louis, Hopital Avicenne and others) under the responsibility of several well-known oncologists. This list of curative centres is not limitative and any clinician wishing to apply for treating patients with SOAz will be warmly welcomed. 

A formal 13+2 -cycloaddi lion can be accomplished by adding bis(2-carbethoxyethyl) zinc to acetylenic esters . This reaction allows the construction of complex cyclopen-tenones, such as 388, which is a precursor of ( )-bilobalide (Scheme 101) . The allylzincation of tiimethylsilylacetylenes can be performed intramolecularly providing a functionalized alkenylzinc which cyclizes in the presence of Pd(PPh3)4 at 25 "C within 3.5 h, leading to the bicyclic product 389 in 84% yield (Scheme 102). The addition of allylic zinc halides to various alkynes occurs in the absence of copper salts. The related... 

In severe ocular bums with complete loss of the limbal vascularization, other than the predictable impossibility of secondary re-epithelialization, there is an immediate risk of necrosis for the anterior segment. In order to restore the limbal circulation and to block the evolution towards a necrosis or an aseptic ulceration, a Tenon s plastics may be realized. It consists in the making of a Tenon s advancement flap located at the level of the limbus [4-8]. The intervention must be realized as soon as the necrotic tissues have been removed. The dissection starts in the equatorial region and continues at the back of the conjunctival sacs. The flaps must be 1-2 mm thick. Their elastic consistency helps their advancement. The flap is sutured to the... 

This technique facilitates the scleral cicatrization and prevents the formation of scleral ulcers but it does not enable the covering of the comeal surface with a normal phenotype comeal epithelium [8]. It does not completely avoid the development of a conjunctival fibrosis or of symblepharons. The formation of sym-blepharons, 28% in Kuckelkom series, is most often recorded within the first three months. This situation may require the realization of a new Tenon s plastics or of a transplant of conjunctiva, nose, or mouth mucous membrane. 

Kuckelkom does not advise the practice of this intervention during the critical phase of the bum but prefers the Tenon s plastics [12]. 

Reim, M., Overkamping, B., Kuckelkom, R. Two years experience with Tenon-plasty. Ophthalmologe 89, 534-540 (1992)... 

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