Dieckmann reaction, retro

The same paper reports another route to 11-membered acetylenic lactones via an intramolecular retro-Dieckmann reaction (equation I). Thus treatment of 3 with... 

A method for the enantioselective synthesis of the ftmctionalised carbapenam core 38 from D-serine-derived pyrrolidines has been reported <03JOC187>. Disubstituted pyrrolidines, obtained from the retro Dieckmann reaction of azabicyclo[2.2.1]heptan-2-one-1-carboxylic acid methyl esters, have been used as starting materials to develop concise syntheses of all four stereoisomers of carbapenam-3-carboxylic acid methyl esters <03JOC2889>. The synthesis of 1-methylcarbapenams 39 by intramolecular attack of lactam nitrogen on a 77 -propargylpalladium complex has been reported <03JOC8068>. 

In Kozikowski s synthesis of showdomycin, treatment of the oxabicyclic 130 with bicarbonate induced a retro-Dieckmann reaction to reveal the highly substituted tetrahydrofuran intermediate 131, Eq. 93 [142]. 

Similarly, treatment of substrate 132 with sodium methoxide led to a retro-Dieckmann reaction to yield the interesting bicyclic ether 133 as a single isomer, Eq.94 [90]. 

The reversibility of the process means that cyclic 2-alkoxycarbonyl ketones can be cleaved by alkoxide in the retro-Dieckmann reaction, a process of synthetic significance (see Section 3.6.9.1). More recently, nonequilibrium conditions have been employed in the reaction and this may lead to a change in regioselectivity (see Section 3.6.3.3.3). 

An acid-catalyzed retro-Dieckmann reaction converts the p-keto ketal (237) into (238a), which can be transesterified to the methyl ester (238b). ° No racemization occurs at the noncleaving ring junction, both enantiomers of (237) proceeding with retention of configuration (Scheme 100). 

As with the forward reaction, the retro-Thorpe-Ziegler reaction has found much less use than the retro-Dieckmann reaction. A Thorpe-Ziegler, retro-Thorpe-Ziegler sequence has been used to a-tetra-methylate the bisnitrile (239 Scheme 101). ... 

Dihydroxynaphthoyl-CoA synthase and Bad Dieckmann and retro-Dieckmann reactions... 

Michael addition, followed by an intramolecular aldol condensation to provide the seven-membered ring. Subsequent retro-Dieckmann reaction, dehydration, and ester saponification provide the bicyclic product in 98% yield. A related cascade reaction was recently reported by the same research group in which the reactions of various allylic halides with cyclopentanone derivatives provide seven-membered rings. ... 

Interestingly ketones can be carbonylated. Reaction of cyclohexanone with CO in MeOH using PdCh and CuCb as catalysts under mild conditions afforded dimethyl pimelate (474) and methyl 6-chlorohexanoate (475) in good yields. Mechanism of the carbonylation is not clear. Dimethyl pimelate (474) is formed by methanolysis (retro-Dieckmann reaction) of methyl cyclohexanonecarboxylate (478) promoted by CuCF and acid. Methyl cyclohexanonecarboxylate (478) may be formed by methoxypalladation of the enolate 476 to form Pd enolate 477, followed by CO insertion. Chlorination of cyclohexanone with CuCl2 gives 2-chlorocyclohexanone 480 which is converted to 475 [197]. 

Michael/Aldol/Retro-Dieckmann Reaction Rodriguez group developed a Michael/aldol/retro-Dieckmann (MARDi) cascade to construct stereoselectively... 

Mahajan has described a novel route to macrocyclic ketolactones using a retro-Dieckmann reaction (Scheme 24). Although perhaps not of general applicability, the method appears attractive for the synthesis of the type of molecule shown in the scheme. The same idea of bond fission of polycyclic systems to form macro-lides has been used to prepare ketolactones from 2,3-polymethylene-benzo- and -naphtho-pyrans by oxidative cleavage (Scheme 25). 

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