Double Addition of Alkynyllithium Reagents to Amides/Lactams: A Direct and Flexible Synthesis of 3-Amino-1,4-diynes Bearing an Aza-Quaternary Carbon Center
in situ activation of amides with trifluoromethanesulfonic anhydride, followed by doubleaddition of alkynyllithium reagents at a concentration of 0.5 mol·L–1 in dichloromethane. This constitutes an extension of the method of direct reductive bisalkylation of amides that allows both employing alkynyllithium reagents as the first-addition nucleophiles and incorporating an alkynyl group as the first-introduced
both boron and titanium(IV) enolates bearing chiral auxiliaries. Reversal of diastereoselectivity was observed by the reactions of the boron and titanium(IV) enolates. Using these reactions, all of the four stereoisomers of α-methyl-β-phenylalanines, for example, can be prepared highly diastereoselectively. Cyclic N-acyloxyiminium ions are useful for the asymmetricsynthesis of pyrrolidine and piperidine
Synthesis of a propargyl alcohol having a C60 cage, its transformation into C60 derivatives with polar functional groups, and the solubility measurements
organic solvents, the propargyl alcohol derived from 4 was allowed to react with succinic anhydride and with diglycolic anhydride to give the corresponding carboxylic acids 6 and 7 having ester groups. In the same manner, the reaction of C60 with tetraethylene glycol derivative of propargyl alcohol afforded the corresponding tetraethylene glycol monoether derivative of C60 (10). The solubility of the
Deoxyazasugars such as deoxymannojirimycin, deoxyaltrojirimycin and deoxygalactostatin were stereoselectively synthesized starting from (R)-(+)-4-methoxycarbonyloxazolidinone via a bicyclic oxazolidinylpiperidine as a common synthetic intermediate.
[3,3]sigmatropic ring expansion of cyclic thionocarbonates. 13.1 synthesis of medium-membered heterocyclic allenes and synthetic application to antifungal constitutent of Sapium japonicum
thionocarbonates (2i-k) afforded a new type of strained 8-membered heterocyclic allenes (3i-k) in high yields. The MNDO optimized structure of 3i indicated the allenyl moiety was bent and strained. The reactivity of 8-membered cyclic allenes was also examined. Further, using this methodology with a novel application of a SmI2-HMPA reduction of the resulting heterocyclic allene (3n), an antifungal constituent