Oxycarbonylation, intramolecular

The intramolecular oxidative earbonylation has wide synthetie applieation. The 7-lactone 247 is prepared by intramolecular oxycarbonylation of the alke-nediol 244 with a stoichiometric amount of Pd(OAc)2 under atmospheric pres-sure[223]. The intermediate 245 is formed by oxypalladation, and subsequent CO insertion gives the acylpalladium 246. The oxycarbonylation of alkenols and alkanediols can be carried out with a catalytic amount of PdCl2 and a stoichiometric amount of CuCb, and has been applied to the synthesis of frenolicin(224] and frendicin B (249) from 248[225]. The carbonylation of the 4-penten-l,3-diol 250, catalyzed by PdCl2 and CuCl2, afforded in the c -3-hydroxytetrahydrofuran-2-aeetie acid lactone 251[226J. The cyclic acetal 253 is prepared from the dienone 252 in the presence of trimethyl orthoformate as an accepter of water formed by the oxidative reaction[227]. 

It has been demonstrated that Bi(OTf)3 is a versatile catalyst for the activation of both ct- and 7t-donors. Thus, in order to evaluate their potential in terms of a ji-donor/71-acceptor interaction, Bi-catalyzed hydroalkynylations were investigated. As an example, Takaki and coworkers developed a Bi(OTf)3-catalyzed intramolecular carbo-oxycarbonylation of alkynyl esters (Scheme 35) [89]. 

Intramolecular oxidative carbonylation has wide synthetic application. The y-lactone 128 is prepared by intramolecular oxycarbonylation of the alkenediol 125 with a stoichiometric amount of Pd(OAc)2 at atmospheric pressure [93]. The intermediate 126 is formed by oxypalladation, and subsequent CO insertion gives the acylpalladium 127. The oxycarbonylation of alkenol and alkenediol can be carried out with a... 

The PL method has been used to investigate the IMM of the maaomolecules of carboxymethylcellulose (CMC) Anthrylacyloxymethane luminescent groups were used as LM. It was found that the presence of the cellobiose units in the main chain or the formation of intramolecular hydrogen bonds leads to a marked decrease in IMM. The value of r for CMC in water is 57 ns. As Tables 11,12 show, these high values of t are characteristic of the IMM of macromolecules with the elements of the internal structure such as polyfmethacrylic acid) (PM AA) in water. For non-ionized PMAA in water, is ca. 77 ns for LM in the side chain 9-anthrylmethyl-oxycarbonyl groups). 

UV Irradiation of an 3-aryl-2-azidoacrylic ester (2-azidocinnamate) results in elimination of nitrogen and formation of a 2/f-azirine, which undergoes spontaneous electrocyclic ring opening to give a reactive intermediate which can react as an azomethine ylide dipole or an alk-oxycarbonyl(benzylidenimino)carbene. In favorable cases, the carbene form can be trapped by intramolecular [l-t-2] cycloaddition to an alkene double bond to give a dihydro-cyclopropa[c]isoquinoline, e.g.l, and 2 (Houben-Weyl, Vol. E19b, pi 166). 

Similar examples of stereo- and regioselective intramolecular oxycarbonylative additions have been reported with oxygen-functionalized 1.3-dienes98 and allenes". 

The unsaturated hydroxy carboxylic acid 152 was converted to the dilactone 153 via domino oxypalladation and carbonylation [63]. The y-lactone 156 was prepared by intramolecular oxycarbonylation of the alkenediol 154. The intermediate 155 is formed by the oxypalladation, and subsequent intramolecular carbonylation affords the lactone 156. The reaction was applied to the synthesis of tetrono-mycin [64]. The oxycarbonylations of alkenol and alkanediol can be carried out with a catalytic amount of PdCl2 and a stoichiometric amount of CuCl2, and have been applied to syntheses of a number of natural products. 

Intramolecular reaction of allenes is known to proceed mainly by palladation at the central carbon to generate alkenylpalladium 235, which undergoes further reactions. Also TT-allylpalladium 236 is formed when a nucleophile attacks the central carbon. The intramolecular aminopalladation of the 6-aminoallene 237, followed by CO insertion, afforded the unsaturated amino ester 238. The reaction has been applied to the enantioselective synthesis of pumiliotoxin [103]. Oxycarbonylation of the allenyl alcohol 239 afforded the unsaturated ester 240 in 83 % yield using a catalytic amount of PdCl2 and 3 equivalents of CuCb in MeOH and is used for the synthesis of rhopaloic acid [104]. 

Intramolecular oxycarbonylation and aminocarbonylation are also known. As an example, frenolicin has been synthesized using oxycarbonylation at 1.1 atm of CO as a key step (eq 28). The intramolecular aminopalladation of a carbamate group and subsequent carbonylation of the substituted 3-hydroxy-4-pentenylamine proceeds smoothly in AcOH (eq 29). ... 

Boukouvalas and co-workers employed an intramolecular oxycarbonylation of benzyl alcohol 89 in the asymmetric synthesis of (—)-panacene, tetrahydrofuroben-zofuran derivative, which holds the prominent position of being the archetypical member of a family of marine bro-moallenes. ° The synthesis of the panacene building block 89 (Scheme 15.22) starts from the aldehyde 87, which is accessed from commercially available 2-methoxy-6-metyl-benzoic acid. An asymmetric alkynylation of 87 followed by reduction of the triple bond with hydrogen over Lindlar... 

Kapitan P, Gracza T. Asymmetric intramolecular Pd(II)-catalysed oxycarbonylation of alkene-l,3-diols. ARKIVOC 2008 viii 8-17. 

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