Propyne 1-methoxy

After the initial claim of the synthesis of an oxirene (by the oxidation of propyne Section 5.05.6.3.1) this system reappeared with the claim 31LA(490)20l) that 2-chloro-l,2-diphenyl-ethanone (110) reacted with sodium methoxide to give diphenyloxirene (111), but it was later shown (52JA2082) that the product was the prosaic methoxy ketone (112 Scheme 97) (the formation of 111 from 110 would be an a-elimination carbene-type reaction). Even with strong, nonnucleophilic bases, (110) failed to provide evidence of diphenyloxirene formation (64JA4866). 

The cycloaddition of Weinreb amide functionalized nitrile oxide with a range of dipolarophiles has been studied. N-Methoxy-N-methylcarbonocyanidic amide, nitrile oxide 207 (i.e., a nitrile oxide of Weinreb amide type derivative) was generated from 2-chloro-2-(hydroxyimino)-N-methoxy-N-methylacetamide as intermediate and used in situ. Thus, addition of 3-bromo-l-propyne as dipolarophile to this precursor of 207, followed by quenching with triethylamine, gave 5-(bromo-methyl)-N-(methoxy)-N-methyl-3-isoxazolecarboxamide 208 in 55% to 60% yield (367). 

The syntheses of findersine (92a) and its methoxy derivative 92b (28 and 35%, respectively) starting from thallous salts of corresponding 2,4-dihy-droxyquinolines and 3-chloro-3-methyl-l-propyne, on the other hand, did not apparently involve a hydration step. 

Methoxy 1 propyne furconazole Methyl acetoacetate see Aceto acetic acid Methyl aceto acetic acid pirimicarb... 

Pd complexed with 2-pyridyldiphenylphosphine (or its 6-methylpyridyl derivative) and weakly coordinating counter ions, such as methylsulfonate, are employed as catalyst [84, 85]. After the coordination of methanol and CO the migration of the methoxy group takes place to form the palladium carbomethoxy species. Then the coordination of propyne takes place. The steric bulk of the pyridyl group, and in particular of the 6-methylpyridyl group, induces the con-... 

The other cycle starts from the other end of the MMA molecule by carbon monoxide insertion in a Pd-methoxy species, followed by propyne insertion in the 7,2 regio-mode in a Pd-carbomethoxy bond and subsequent termination by protonolysis of the Pd-alkenyl bond to give MMA and a regenerated Pd-methoxy species (Scheme IB). In this cycle, methyl crotonate is formed by insertion in the 2,1 regio-mode. 

The experimental observations (Figure 2) thus strongly indicate that carbonyla-tion of propyne with the present group of catalysts actually proceeds via the Pd-methoxy cycle (B) in Scheme 1 [11]. 

Although desirable, it is generally difficult to obtain direct experimental evidence on the transition states and detailed pathways of individual elementary steps in a catalytic cycle. It may then be useful to apply the technique of computer-assisted molecular modeling as the next-best alternative, to obtain relevant information on proposed elementary reactions of a catalytic cycle (cf. Section 3.1.2). The results of molecular modeling studies, which we undertook to obtain a more detailed, though qualitative, understanding of some elementary steps in the above mentioned Pd-methoxy cycle for propyne carbonylation, are summarized below. 

Obviously, ligands containing the 2-pyridylphosphine moiety combine all the necessary properties to function not only as a selectivity-determining bidentate ligand, but also as an ideal proton transfer catalyst. This leads to the proposed catalytic Pd-methoxy cycle for carbonylation of propyne by cationic palladium/ 2-pyridylphosphine catalyst systems as shown in Scheme 4. 

Cyclizations. Substituted furans are formed from HgClj-catalyzed cyclization of allenyl carbinols which are derived from 3-methoxy-l-phenylthio-l-propyne. ... 

C4HsOf 3-Methyl-3-methoxy propyne, 3-thiomethoxy-3-methoxy propyne 3, 3-dimethoxy propyne 150 g,i 827... 

D-Glucose orthoesters of complex alcohols can be easily obtained with the help of silver salicylate Alcohols and amines can be conveniently prepared from olefins by ozonization-reduction and ozoni-zation-reductive amination respectively without isolation of intermediates Inverted amines can be obtained from optically-active alcohols through stereospecific formation of N-alkylphthalimides 3-Methoxy-l-phenyl-l-propyne has been used as starting material for the synthesis of a,/ -unsatd. carbonyl compounds through allenic di-carbanions a-Ketocarboxylic acids can be easily prepared from cyanohydrins through a Ritter reaction... 

Propanol, [2(2-methoxy-methylefhoxy)methylethoxyl] Propargyl alcohol (2-propyn-l-ol)... 

Substituted 1-halo and 1-alkoxy isoquinolines are formed from A/-methoxy benzimidoyl halides and alkynes with a ruthenium catalyst (Scheme 59) (13CC3703). The reaction with an unsymmetrical alkyne, 1-phenyl-l-propyne, occurs regioselectively, with the phenyl adding adjacent to the nitrogen. The reaction occurs with both imidoyl chlorides and... 

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