Butadiene methoxycarbonylation

For this reaction, the early investigations of Reppe pointed out the need for catalyst precursors to operate at high pressure [2], It is necessary to work at 150-300 bar of CO in order to stabilize the two catalytic species [Co(H)(CO)4] or [Ni(H)(X)(CO)2] that adopt a mechanism analogous to the cobalt-catalyzed hydroformylation [44,45]. Many industrial applications have been reported [28,46,47] for the synthesis of plasticizers and detergents. Similarly, the two-step methoxycarbonylation of 1,3-butadiene has been explored by BASF and other companies to produce dimethyl 1,6-hexanedioate (adipate) directly from the C4 cut [28,48]. The first step operates at 130 °C and... 

In a similar way, 2-(methoxycarbonyl)-l,3-butadiene (39) dimerizes rapidly, even in the presence of electron-rich dienes such as 40a or 40b, as illustrated in equation 1865. The dimeric adduct 41 and the mixed adduct 42 were obtained in ratios of 90 10 and 75 25 in the reactions of 39 with 40a and 40b, respectively. 

Ceric ammonium nitrate promoted oxidative addition of silyl enol ethers to 1,3-butadiene affords 1 1 mixtures of 4-(/J-oxoalkyl)-substituted 3-nitroxy-l-butene and l-nitroxy-2-butene27. Palladium(0)-catalyzed alkylation of the nitroxy isomeric mixture takes place through a common ij3 palladium complex which undergoes nucleophilic attack almost exclusively at the less substituted allylic carbon. Thus, oxidative addition of the silyl enol ether of 1-indanone to 1,3-butadiene followed by palladium-catalyzed substitution with sodium dimethyl malonate afforded 42% of a 19 1 mixture of methyl ( )-2-(methoxycarbonyl)-6-(l-oxo-2-indanyl)-4-hexenoate (5) and methyl 2-(methoxycarbonyl)-4-(l-oxo-2-indanyl)-3-vinylbutanoate (6), respectively (equation 12). 

Although Fe(CO)rcomplexed butadiene does not react with dibromocarbene, the corresponding penta-1,3-dienes undergo C-H insertion at the sp3 carbon atom (27-38%) [15], Metal carbonyl-complexed cyclohexadiene and 1-methoxycarbonyl-1,2-dihydropyridine also react in a similar manner in 31 and 54% yield, respectively. 

Diese Reaktionsart ist bei den Addukten aus Butadien-carbonsaure-Derivaten mit der Carboxylgmppe in 3-Stellung allein verwirklicht dabei entstehen 3-Amino-a-pyrone [58, 70, 72). So geht das N-p-Chlorphenyl-3-methoxycarbonyl-6-phenyl-3.6-dihydro-1.2-oxazin bei der Chromato-graphie an Aluminiumoxid in 3-p-Chloranilino-6-phenyl-a-pyron uber (55), der Mechanismus ist analog dem der Pyrrolbildung. 

E. [l,4-BIS(METHOXYCARBONYL)-2-METHYL-3-PHENYL-l,3-BUTADIENE-1,4-DIYL]-(ti5-CYCLOPENTADIENYL)-(TRIPHENYLPHOSPHINE) COBALT AND [1,3-BIS(METHOX YCARBONYL)-2-METH YL-4-PHENYL-1,3-BUT ADIENE-1,4-DI YL]-(q 5-C Y CLOPENT ADIENYL)-(TRIPHENYLPHOSPHINE)COBALTt... 

Bis(methoxycarbonyl)-2-methyl-3-phenyl-l, 3-butadiene-1,4-diyl]cobalt=2,5-dicarbo-methoxy-3-phenyl-4-methylcobaltacyclopentadiene. 

CoClPjC H, Cobalt, chlorotris-(triphenylphosphine)-, 26 190 CoN203C15H9, Cobalt, tricarbonyl[2-(phenylazo)phenyl-C, A ]-, 26 176 CoO PC3jHm, Cobalt, (V 2-propynoate) (triphenylphosphine)-, 26 192 CoC PCmH, Cobalt, (Ty -cyclopentadienyl) [ 1,3-bis(methoxycarbonyl)-2-methyl-4-phenyl-l, 3-butadiene-1,4-diyl]-(triphenylphosphine)-, 26 197... 

OjCoPCmHjj, Cobalt, (i)J-cyclopenta-dienyl)-[l,3-bis(methoxycarbonyl)-2-methyl-4-phenyl-1,3-butadiene-1.4-diyl)-(triphenylphosphine)-, 26 197... 

The X-ray crystal structure of the 1 -tosyl-1H-1,2-diazepine (10) shows a boat conformation with N(l) at the prow (Figure 1) (72T581). Double bonds are clearly localized at N(2)—C(3) 1.255 A, C(4)—C(5) 1.326 A, and C(6)—C(7) 1.333 A, and the imine bond is isolated, whereas bond delocalization is present in the butadiene-like part C(4)—C(5)—C(6)—C(7). In contrast, when the diazepine is complexed with Fe(CO)3, for example (11), the iron atom is bound to the butadiene moiety C(4) to C(7), as also occurs in the lf/-azepine and l-methoxycarbonyl-l//-azepine complexes the N(l) atom adopts a planar sp2 configuration and the seven-membered ring consists of the two planar parts bent along the C(4)... C(7) line by 140° (70AG(E)958). 

An approach to the synthesis of angularly substituted polycyclics through the Diels-Alder cycloaddition of dihydrothiophenes has been devised (69JA7780). The easily prepared 2,5-dihydro-4-methoxycarbonyl-2-thiopheneacetic acid methyl ester (316) was heated at 180 °C with excess butadiene to yield (317). Desulfurization and double bond reduction of the cycloadduct with W-5 Raney nickel gave (318) which was characterized by conversion to the corresponding diacid and comparison with an authentic sample. Dieckmann cyclization of (318) is known to lead to the 5-methyl-1-hydrindanone (319 Scheme 68). The use of other dienes in the [4 + 2] cycloaddition process will, of course, produce more highly functionalized hydrindanones. 

D. trans-4,7,7-Tricarbomethoxy-2-phenylsulfonylbicyclo[3.3.0]oct-1-ene. In a flame-dried, 2-L, three-necked, round-bottomed flask equipped with a magnetic stirrer, dropping funnel, and nitrogen inlet, is placed 1.44 g of sodium hydride (60% in oil, 36.0 mmol) which has been washed twice with 50 mL of hexane and then suspended In 500 mL of anhydrous THF. To the above mixture is added 7.59 g (33.0 mmol) of dimethyl (E)-5-methoxycarbonyl-2-hexenedioate in 50 mL of THF. After being stirred at 0°C for 30 min, a solution containing 10.02 g (30.0 mmol) of 2,3-bis(phenylsulfonyl)-1,3-butadiene in 900 mL of anhydrous THF is added over 30 min. The solution is stirred for 10 min at 0°C and then quenched with 100 mL of a saturated aqueous ammonium chloride solution. The solvent is removed under reduced pressure, and... 

The active species in the methoxycarbonylation is presumably CoH(CO)4 (in equilibrium with Co2(CO)g and Co(CO)4 ) which adds Co-H 1,4- to the diene this is followed by carbonylation of the Co-C bond, methanolysis of the RCO-Co bond by MeOH or OMe , and regeneration of the hydride. The methoxycarbonylation route to adipic acid is an alternative both to the du Pont (Ni(II)/Lewis acid (BPhs)) catalyzed double hydrocyanation of butadiene (Section 5.4.4) and to the process based on the oxidation of cyclohexane (Section 2.2). 

Azepin 1 -Acetyl-2-methoxy-4,5,6,7-tetrahydro- El 5/2, 1778 (a-OR-imin +R-CO-C1) Bernsteinsaure 3-Methyl- -1-butylester-4-nitril VIII, 270 Bicyclo 3.1.1 beptan 6-Hydroximi-nomethyl-(2/ ,6S)-2-hydroxy-6-methyl- IV/5a, 721 Bicyclo 4.1.0 heptan 7-entfo-Amino-7-methoxycarbonyl- E21c, 3266 (cycl. En + cycl. N-CH2-C(OR) = N) 1,3-Butadien 1-Diethylaminocarbo-nyloxy- EI5/1, 14 (En-al + Cl-CO-NR2)... 

PCoOjCjsHjk, Cobalt, (ri -cyclopenta-dienyl)(methyl 3-phenyl-T] -2-propy-noate)(triphenylphosphine)-, 26 192 PC0O4CMH34, Cobalt, (T) -cyclopenta-dienyl)[l,3-bis(methoxycarbonyl)-2-methyl-4-phenyl-1,3-butadiene-1,4-diyl](triphenylphosphine)-, 26 197 PCoOjCwHvi, Cobalt, (ti -cyclopenta-dienyl)[ 1,4-bis(methoxycarbonyl)-2-methyl-3-phenyl-1,3-butadiene-l, 4-diyl](triphenylphosphine)-, 26 197 PCo,FeO,PCi,H5, Iron, nonacarbonyl(pr phenylphosphinidene)dicobalt-, 26 353 PCs404iiV W , Divanadodecatungstophos-phate(5-), p- and -y-, pentacesium, 27 102, 103... 

Another example is the preparation of l,2-di(methoxycarbonyl)-4-cyclopentanone. This compound has been prepared from dimethylmaleate as a mixture of its cis- and trans-isomers (yield 45-55 %) 235). A second approach starts with the Diels-Alder adduct of 1,3-butadiene and maleic anhydride and leads to the trans-diacid (yield 40 %)236). The oldest preparation of 1,2-di(methoxycarbonyl)-4-cyclopentanone stems from Auwers in 189 3 237). Now, the trans-isomer is available from methylenecyclopropane and dialkylfumerate in an overall yield of 85 %, whereas the pure m-isomer can be obtained from methylenecyclopropane and dialkylmaleate in 53 % yield. With dimethylmaleate, the Pd(0) catalyzed codimerization leads to a cis/trans-mixture of 4-methylene-l,2-cyclopentane-dimethylcarboxylate in the ratio 8 2 under optimal conditions (see Table 11) after oxidation, the pure c/ s-cyclopentanone derivative can be isolated by simple crystallization from pentane 193 195>. 

BASF has developed the synthesis of AA by the methoxycarbonylation of butadiene [32a] the catalyst is based on Co. The process takes place in three steps (Scheme 7.9). 

In an alternative synthetic pathway, methyl 5-formylvalerate can be prepared from butadiene via sequential methoxycarbonylation to methyl 3-pentenoate, isomerization to methyl 4-pentenoate, and hydroformylation to methyl 5-formylvalerate. The valerate can then be oxidized to monomethyladipate, which in turn is hydrolyzed to AA (Scheme 7.11). 

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