Allylic ethers copper catalyzed

Tab. 10.8 summarizes the application of rhodium-catalyzed allylic etherification to a variety of racemic secondary allylic carbonates, using the copper(I) alkoxide derived from 2,4-dimethyl-3-pentanol vide intro). Although the allyhc etherification is tolerant of linear alkyl substituents (entries 1-4), branched derivatives proved more challenging in terms of selectivity and turnover, the y-position being the first point at which branching does not appear to interfere with the substitution (entry 5). The allylic etherification also proved feasible for hydroxymethyl, alkene, and aryl substituents, albeit with lower selectivity (entries 6-9). This transformation is remarkably tolerant, given that the classical alkylation of a hindered metal alkoxide with a secondary alkyl halide would undoubtedly lead to elimination. Hence, regioselective rhodium-catalyzed allylic etherification with a secondary copper(l) alkoxide provides an important method for the synthesis of allylic ethers. 

HCA478). A similar route to quinolines via 1,2- dihydroquinolines starts fromN-propargyl-anilines and is copper catalyzed (62JOC4713). The allyl ether of cyclohexanone oxime (126) heated in benzene at 200 °C gives 5,6,7,8-tetrahydroquinoline (79S221) the proposed mechanism is reinforced by the isolation of a compound (128) formed from the ether (126) and a suggested intermediate (127). 

The copper-catalyzed photobicyclization of acyclic 1,6-dienes to bicyclo[3.2,0]heptanes using the bis[copper(l) lrifluoromethanesulfonate]benzene complex has found general and synthetic utility in the conversion of diallyl and homoallyl vinyl ethers to 3- or 2-oxabicyclo[3.2.0]heptanes,5 6 of /V-allyl-A -2-methyl-2-propenecarbamates to iV-carboethoxy-3-azabicyclo[3.2.0]heptanes 7 and of allylic alcohols to the corresponding hydroxy-substituted bicyclo[3.2.0]heptanes.8 9 Examples of such reactions are summarized below. 

Copper-catalyzed reactions of [(tosylimino)iodo]benzene with unsaturated compounds sometimes lead to tosylamidation. Examples include conversions of silyl enol ethers to a-tosylamido ketones [173], and tosylamidation of allylic silanes with loss of the silyl group [190] (Scheme 69). 

Salomon has recendy investigated the coi er(I) triflate catalyzed photocycloadditions of allylic alcohols and allylic ethers in an effort to improve the selectivity in photocycloadditions of unactivated al-kenes (equations 103-105,108). ° One particularly interesting case is illustrated in equation (104), where Ae more sterically hindered product is produced as a result of the photocycloaddition of a rigidly held tridentate copper complex. McMurry has also utilized a copper(I) catalyzed [2 + 2] photocycloaddition in the synthesis of -panisene (equation 106)."° Interestingly, the noncatalyzed cycloaddition shown in equation (107), which might also produce a precursor for p-panisene, was unsuccessful. 

The copper-catalyzed rearrangement of vinylcyclopropane (59) was thought to involve the ir-allyl systems (60a) and (60b) (Scheme 13). The regioselectivity of this rearrangement was only two-fold however, both enol ethers (61) and (62) can be hydrolyzed to the 1,4-dicarbonyl system (63). Platinum- and rhodium-catalyzed decomposition of (59) yielded denes. 

Allyl vinyl ethers may be prepared via stereospecific copper-catalyzed coupling of allyl alcohols and vinyl halides. For example, the copper catalyst derived from the tetramethyl 1,10-phenanthroline ligand shown below facilitates C-0 bond formation between ( )-vinyl iodides and allyl alcohols when the reaction mixture is heated in the presence of air. ... 

Allyldiethylamine behaves similarly, but the yields are low since neither the starting amine nor the products are stable to the reaction conditions. For the efficiency of the cyclopropanation of the allylic systems under discussion, a comparison can be made between the triplet-sensitized photochemical reaction and the process carried out in the presence of copper or rhodium catalysts whereas with allyl halides and allyl ethers, the transition metal catalyzed reaction often produces higher yields (especially if tetraacetatodirhodium is used), the photochemical variant is the method of choice for allyl sulfides. The catalysts react with allyl sulfides (and with allyl selenides and allylamines, for that matter) exclusively via the ylide pathway (see Section 1.2.1.2.4.2.6.3.3. and Houben-Weyl, Vol. E19b, pll30). It should also be noted that the purely thermal decomposition of dimethyl diazomalonate in allyl sulfides produces no cyclopropane, but only the ylide-derived product in high yield.Very few cyclopropanes have been synthesized by photolysis of other diazocarbonyl compounds than a-diazo esters and a-diazo ketones, although this should not be impossible in several cases (e.g. a-diazo aldehydes, a-diazocarboxamides). Irradiation of a-diazo-a-(4-nitrophenyl)acetic acid in a mixture of 2-methylbut-2-ene and methanol gave mainly l-(4-nitrophenyl)-2,2,3-trimethylcyclo-propane-1-carboxylic acid (19, 71%) in addition to some O-H insertion product (10%). ... 

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