Methoxy methyl ligand

By careful optimization, Widdowson and coworkers were able to show that methoxy-methyl ethers of phenols are better substrates for alkyllithium-diamine controlled enan-tioselective deprotonation, and (—)-sparteine 362 is then also the best ligand among those surveyed the BuLi-(—)-sparteine complex deprotonates 447 to give, after electrophilic quench, compounds such as 449 in 58% yield and 92% ee (Scheme 180) . Deprotonation of the anisole complex 410 (see Scheme 169) under these conditions gave products of opposite absolute stereochemistry with poor ee. 

Another example is tetrameric methoxy(methyl)zinc, (MeZnOMe)4. The mechanism can be treated both as an aggregative process as well as a ligand coordination exchange process. It reveals aggregation due solely to oxygen bridging, with no direct participation of the C—Zn bond, and will be mentioned only briefly. 

In order to test whether the base exerts an essential influence on the subsequent reaction of the carbene ligand, we also decomposed pcnta-carbonyl[methoxy( methyl) carbene chromiumfO) purely thermally at 150°C in Decalin. Under these conditions we observed exclusively the formation of carbene dimers—as a mixture of cis and trans isomers (74)— thereby confirming the influence of the base ... 

Of subsequent interest to us was the question of whether a third kind of ligand in the starting carbene complex could influence the orientation of the halogen in the eventual carbyne complex. Therefore, we first treated cis-tetracarbonyl[methoxy(methyl) carbene trimethylphosphine-, -arsine-,... 

When the intramolecular chelating group see Chelating Ligands) is a methoxy-methyl-ether (MOM) in y-position, an... 

Imidazolinyl) derivative of 8-methyl-2,3,6,7-tetrahydro-5 f- and 8-methyl-7-methoxy-5-oxo-2,3-dihydro-5 f-pyrido[l, 2, i-de]-1,4-benzoxazines were included in a 3D-QSAR CoMFA study on imidazolinergic I2 ligands (00JMC1109). 

The reaction of alkoxyarylcarbene complexes with alkynes mainly affords Dotz benzannulated [3C+2S+1C0] cycloadducts. However, uncommon reaction pathways of some alkoxyarylcarbene complexes in their reaction with alkynes leading to indene derivatives in a formal [3C+2S] cycloaddition process have been reported. For example, the reaction of methoxy(2,6-dimethylphenyl)chromium carbene complex with 1,2-diphenylacetylene at 100 °C gives rise to an unusual indene derivative where a sigmatropic 1,5-methyl shift is observed [60]. Moreover, a related (4-hydroxy-2,6-dimethylphenyl)carbene complex reacts in benzene at 100 °C with 3-hexyne to produce an indene derivative. However, the expected Dotz cycloadduct is obtained when the solvent is changed to acetonitrile [61] (Scheme 19). Also, Dotz et al. have shown that the introduction of an isocyanide ligand into the coordination sphere of the metal induces the preferential formation of indene derivatives [62]. 

Almost diastereomerically pure (2i ,55)-l,3-diaza-2-methoxy-3-alkyl-2-phosphabicyclo[3.3.0]octanes (201a-d) were formed in the reaction of (S)-2-anilinomethyl)-pyrrolidines (197b-e) with methyl dichlorophosphite in the presence of NEt3 (Scheme 55) [86], With these ligands, high stereoselectivity (ee s up to 91%) was observed in the Pd catalyzed ally lie animation reaction [86],... 

In the case of 2,5-cyclohexadienone 70, with a methoxy and a methyl substituent (Scheme 7.19), the syn monoadduct 71 gave 3,4,4,5-tetrasubstituted cyclohexanones, with three consecutive stereocenters. On employing the R, S, S)-ligand 18 in the second addition step, cis-72 (98% de) was found, whereas with (S, R,R)-18 in the second step trans-73 (98% de) was obtained [73]. 

Kinetic parameters k, often also and AS, occasionally AV ) for formation and dissociation of several pentacyanoferrate(II) complexes [Fe(CN)5L]" have been established. Ligands L include several S- and A-donor heterocycles,4-methyl- and 4-amino-pyridines, a series of alkylamines, 3- and 4-hydroxy- and 3- and 4-methoxy-pyridines, several amino acids, nicotinamide, " 4-pyridine aldoxime, 3-Me and 3-Ph sydnones, several bis-pyridine ligands,neutral, protonated, and methylated 4,4 -bipyridyl, 1,2-bis(4-pyridyl)ethane and traTO-l,2-bis0-pyridyl)ethene, pyrazine- 4,4 -bipyridyl- and bis(4-pyridyl)ethyne-pentaammine-cobalt(III), edta-ruthenium(III), and pentaammineruthenium-(II)and-(III) complexes of... 

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