5891-25-8

Upstream product

• 61317-72-4 4,4-dimethylpent-1-yn-3-ol 
• 3282-30-2 pivaloyl chloride 
• 1066-54-2 trimethylsilylacetylene 
• 53723-94-7 4,4-dimethyl-1-(trimethylsilyl)pent-1-yn-3-one 
• 14630-40-1 Bis(trimethylsilyl)ethyne 
• 64214-60-4 N-methoxy-N-methylpivalamide 

Downstream Products

• 1207535-16-7 3-(2,4,6-trimethoxyphenyl)-1-t-butyl-2-propyn-1-one 
• 1003-86-7 3-tert-butyl-isoxazole 
• 1122-01-6 5-tert-Butyl-isoxazol 

Relevant academic research and scientific papers

Gold-catalyzed ethynylation of arenes

(Figure Presented) A novel gold-catalyzed ethynylation of aromatic rings with electron-deficient alkynes via gold catalyzed C-H activation of both C sp-H and Csp2-H bonds has been developed. This transformation provides aromatic propiolates difficult to prepare by other methods, highlighting the synthetic potential of gold chemistry.

Mutation of cysteine-295 to alanine in secondary alcohol dehydrogenase from thermoanaerobacter ethanolicus affects the enantioselectivity and substrate specificity of ketone reductions

The mutation of Cys-295 to alanine in Thermoanaerobacter ethanolicus secondary alcohol dehycrogenase (SADH) was performed to give C295A SADH, on the basis of molecular modeling studies utilizing the X-ray crystal structure coordinates of the highly homologous T. brockii secondary alcohol dehydrogenase (YKF.PDB). This mutant SADH has activity for 2-propanol comparable to wild-type SADH. However, the C295A mutation was found to cause a significant shift of enantioselectivity toward the (S)-configuration in the reduction of some ethynylketones to the corresponding chiral propargyl alcohols. This result confirms our prediction that Cys-295 is part of a small alkyl group binding pocket whose size determines the binding orientation of ketone substrates, and, hence, the stereochemical configuration of the product alcohol. Furthermore, C295A SADH has much higher actifity towards t-butyl and some α-branched ketones than does wild-type SADH. The C295A mutation does not affect the thioester reductase activity of SADH. The broader substrate specificity and altered stereoselectivity for C295A SADH make it a potentially useful tool for asymmetric reductions. Copyright

Asymmetric reduction of ethynyl ketones and ethynylketoesters by secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus

Secondary alcohol dehydrogenase (SADH) from Thermoanaerobacter ethanolicus, an NADP-dependent, thermostable oxidoreductase, reduces ethynyl ketones and ethynylketoesters enantioselectively to the corresponding propargyl (propargyl = prop-2-ynyl) alcohols. Ethynyl ketones, in general, are reduced with moderate enantioselectivity (with the exception of 4-methylpent-l-yn-3-one, which gives the (S)-alcohol with >98% ee). Although ethynyl ketones bearing a small (up to n-propyl) alkyl substituent are reduced to (S)-alcohols, larger ethynyl ketones give (R)-alcohols. In contrast, ethynylketoesters are converted to (R)-ethynylhydroxyesters of excellent optical purity. Unexpectedly, isopropyl ethynylketoesters give higher chemical yields and higher enantioselectivities of ethynylhydroxyesters than methyl or ethyl ethynylketoesters. The optically pure ethynylhydroxyesters may serve as useful chiral building blocks for asymmetric synthesis.

Reactions of Carbonyl-Conjugated Alkynes with N-Bromosuccinimide and N-Iodosuccinimide in DMF/H2O and Methanol/Sulfuric Acid: Syntheses of Dihalo Diketones, Dihalo Ketoesters, and Dihalo Acetals

The following terminal, carbonyl-conjugated alkynes were reacted with N- bromosuccinimide (NBS) and N-iodosuccinimide (NIS) in MeOH/H2SO4 to give dibromo and diiodo acetals in the indicated yields: 3-butyn-2-one, 1: NBS (75%), NIS (95%); 1-phenyl-1-propyn-l-one, 2: NBS (90%), NIS (40%); 1-hexyn-3-one, 3: NBS (90%), NIS (70%); methyl propiolate, 4: NBS (20%, not isolated), NIS (95%). 4,4-Dimethyl-l-pentyn-3-one (5) gave only a trace of dibromo acetal and no diiodo acetal; tribromide and tetrabromide were the major products. NBS and NIS reactions required, respectively, 20% and 33 wt % of H2SO4. The reaction was unsuccessful with internal alkynes 4-phenyl-3-butyn-2-one and 3-hexyn-2-one which gave only complex mixtures of products. Alkyne 2 gave a significant yield of acetal-ketal in addition to the dihalo acetals. Both the dibromo acetal- ketal and diiodo acetal-ketal were isolated, but only the former could be hydrolyzed to the dibromo acetal. Internal, carbonyl-conjugated alkynes reacted with NBS and NIS in H2O/DMF (40:60) to give the following products in the indicated yields: 4-phenyl-3-butyn-2-one (6): 1-phenyl-3,3- dibromo-1,3-butanedione (17, 70%), 1-phenyl-3,3-diiodo-1,3-butanedione (21, 95%); 3-hexyn-2-one (7): 3,3-dibromo-2,4-hexanedione (18, 80%), 3,3-diiodo-2,4-hexanedione (22, 95%); methyl 3- phenyl-2-propynoate (8): methyl 2,2-dibromo-3-keto-3-phenylpropanoate (19, 43%), methyl 2,2- diiodo-3-keto-3-phenylpropanoate (23, 95%); methyl 2-pentynoate (9): methyl 2,2-dibromo-3- ketopentanoate (20, 80%), methyl 2,2-diiodo-3-ketopentanoate (24, 95%). All reactions, except for 6 and 8 with NBS, required H2-SO4. The terminal, carbonyl-conjugated alkyne, 3-butyn-2-one, did not give products, possibly because of oxidation of the intermediate aldehyde by NBS and NIS. Mechanisms involving electrophilic attack by halogen on the triple bond and an acid-catalyzed mechanism are discussed.

A convenient synthesis of masked β-ketoaldehydes by the controlled addition of nucleophiles to (trimethylsilyl)ethynyl ketones

The controlled addition of nucleophiles to (trimethylsilyl)ethynyl ketones provides a facile route to β-ketoacetals, β-alkoxy-α,β-unsaturated ketones or vinylogous amides depending on the choice of reaction conditions.