Deprotections palladium® acetate

In a related study, the precursor 41 could be amiulated either by irradiation or by treatment with palladium acetate in acetic acid to provide indolocarbazoles 42 and 43 in yields of 37% and 55%, respectively (Scheme 8). Both products were eventually deprotected efficiently to give 44 and transformed further under reductive conditions to staurosporinone 45, the aglycone of 8, Alternatively, a shorter route encompassing deprotection of 41, followed by cychzation by irradiation in the presence of iodine and subsequent reduction, gave 45 in an even better overall yield (98T6909). 

The bromo derivative of A -mcthylsuccinimide did also undergo Suzuki coupling when treated with naphthylboronic acid in the presence of palladium acetate, triphenylphosphine and potassium carbonate (6.3.). The coupled product was deprotected under the reaction conditions and an indole derivative was isolated in good yield, which was successfully converted into the hexacyclic naphthopyrrolo[3,4-c]carbazole structure. Using the analogous trimethylstannyl-naphthalene derivative and optimised Stille coupling conditions the desired product was isolated only in 56% yield.5... 

Benzylphosphonates can be deprotected with palladium acetate under increased hydrogen pressure with simultaneous cleavage from the support. ... 

Synthesis of isomeric chiral protected (63 )-6-amino-hexahydro-2,7-dioxopyrazolo[l,2- ]pyrazole-l-carboxylic acid 280 is shown in Scheme 36. Crude vinyl phosphonate 275, obtained by treatment of diethyl allyloxycarbonylmethyl-phosphonate with acetic anhydride and tetramethyl diaminomethane as a formaldehyde equivalent, was used in the Michael addition to chiral 4-(f-butoxycarbonylamino)pyrazolidin-3-one 272. The Michael addition is run in dichloro-methane followed by addition of f-butyl oxalyl chloride and 2 equiv of Huning s base in the same pot to provide 276 in 58% yield. The allyl ester is deprotected using palladium catalysis to give the corresponding acid 277, which is... 

The 5-iodo derivative 1016 was prepared by reaction of the acetate of 999 with iodine monochloride, and subsequent deprotection using sodium methoxide in methanol. The protected derivative 1016 is a suitable precursor for use in cross-coupling reactions to prepare the unsaturated analogs 1018 and 1019. Thus, reaction of 1016 with methyl acrylate in the presence of palladium(II) acetate gave the ( )-5-(2-methoxycarbonylvinyl)uracil 1017 this was converted into the ( )-5-(2-bromovinyl) analog 1019 by alkaline... 

Palladium-catalyzed, Allylic Amination. Allylic substitution of mono-saccharidic hex-2-enopyranoside 4-acetates with secondary amines in the presence of tetrakis (triphenylphosphine)palladium(O) liad led to a large variety of 4-aminated 2-enosides, with retention of configuration (56-58). The method was applied to the disaccaridic enoside 1 to give, with benzylmethylamine or dibenzylamine, the 4-amino sugar derivatives g in yields of 92 and 67% (46). Studies concerning hydrox-ylation of t)ie double bond and subsequent deprotection are incomplete. 

Deprotection of allyl or allyloxycarbonyl derivatives of amino acids.1 This combination of reagents effects rapid reductive cleavage of allyl or allyloxycarbonyl derivatives of amino acids in CH2C12 containing a proton donor (p-N02C6H50H, acetic add, H20). The actual catalyst is probably bis(triphenylphosphine)palladium(0). Benzyl, Boc, and Cbo groups are stable to these conditions. This cleavage does not induce racemization. 

The desymmetrization of dicarbonate 206 was initiated by the addition of one equivalent of N-(3-butenyl) nosylamide 207 under palladium catalysis in the presence of Trost s chiral diphosphine ligand 205. When the first allylic substitution was completed, the reaction was warmed and the resulting intermediate 208 was treated in situ with one equivalent of a second nosylamide 209. Product 210 resulting from this double substitution reaction was submitted to a tandem intramolecular ROM/RCM to furnish key precursor 211, which was engaged in the final cyc-lization step by the reduction of the double bonds, followed by the HCl-promoted domino deprotection of the acetal and aminal formation. 

The reactions of arylation of heterocyclic /3-ketoesters were employed in the synthesis of a number of isoflavanones and isoflavones.27,28 cr-Methylene cr-arylketones can be easily and selectively obtained by arylation of allyl /3-ketoesters which are eventually deprotected by the Tsuji s procedures. a Deallyloxycarbonylation was performed by treatment of the allyl cr-aryl-/3-ketoesters with catalytic amounts of palladium(n) acetate, triethylammo-nium formate and triphenylphosphane in THF at room temperature and afforded the a-arylketones in 75-97% yield.27 Deallyloxycarbonylation-dehydrogenation can be realized with the same allyl esters by treatment with catalytic amounts of palladium(n) acetate and l,2-bis(diphenylphosphino)ethane (DPPE) in acetonitrile under reflux and affords the ct-aryl cr,/3-unsaturated ketones in 60-90% yield (Scheme 4).28 In particular, this reaction was used in a direct convergent synthesis of 2 -hydroxyisoflavones involving arylation of an appropriate allyl /3-ketoester with the MOM-protected (2-methoxymethoxyphenyl)lead triacetate derivative (Scheme 4). The reaction of the isomeric... 

Genet and co-workers devised a water soluble Pd(0) catalyst, [prepared in situ from palladium(II) acetate and trisodium 3,3, 3 -phosphinetriyltribenzenesulfo-nate (TPPTS)] that can be used to deprotect base sensitive penem allyl ester... 

Deprotection of the chiral auxiliary groups is performed using ammonium formate, acetic acid, and palladium hydroxide in refluxing ethanol (eq 2). This sequence gives, after purification by distillation, the free optically pure (/J,/J)-diamine 3. ... 

In addition to the functionalization protocols of Schemes 13 and 14, vinylic substitution reactions involving metalation and palladium-mediated carbon-carbon bond formation have been formulated," which further broaden the variety of stmctural types available from the Patemo-BUchi reaction. For example, deprotection and stannylation of photoaldol (133), followed by refimctionalization of the a-enol ether position of vinylstannane (134), gave the substituted oxetane (135) in good overall yield. Similar functionalization of bicyclic oxetane (136) via exo-face dihydroxylation and acid-catalyzed reorganization of the acetal to the protected 3-deoxy-( )-streptose (137) has been reported, which illustrates the synthetic utility of such processes in the synthesis of polyoxygenated materials." ... 

The complete NAG-NAM-NAG-NAM sequence (20) was in place after the removal of the DMM groups and the acetate groups at the C3 position of the NAM rings, followed by incorporation of the lactate functionality at the C3 position (Figure 3). p-Nitrophenyl activation of compound 20 was used for the formation of the amide bond between the lactate moiety and L-Ala of the protected pentapeptide. A final global deprotection of the fully protected tetrasaccharide pentapeptide 21 by hydrogenolysis over palladium gave the desired compound 8. 

Although there are numerous methods for the protection and deprotection of diacetyl acetals, these are rarely used in synthesis as protective groups, but have been used as starting materials for palladium-catalyzed alkylations. ... 

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