Yun-Yan Kuang

Generation of β-Halo Vinylsulfones through a Multicomponent Reaction with Insertion of Sulfur Dioxide

A four-component reaction of terminal alkynes, aryldiazonium tetrafluoroborates, sulfur dioxide surrogate of DABCO⋅(SO2 )2 , and potassium halide in the presence of copper(I) chloride (10 mol %) gives rise to β-halo vinylsulfones with good stereoselectivity. The vicinal difunctionalization of alkynes through sulfonylation and halogenation with the insertion of sulfur dioxide works efficiently. A plausible mechanism is proposed, which includes a radical process.

A Novel and Practical Synthesis of 2-Amino-5-hydroxypropiophenone

In connection with our recent development of an efficient asymmetric total synthesis of irinotecan (CPT-11, 1), an analogue of the natural product camptothecin, approved by the FDA for treatment of refractory colorectal cancer,1,2 2-amino-5-hydroxypropiophenone (2) was required as a key intermediate for the construction of the AB ring with (4 ′ S)-tricyclic hydroxylactone 3, another known intermediate bearing CDE ring skeleton for the synthesis of CPT-11 through a Friedlander condensation strategy.3 Two precedents for the preparation of this intermediate 2 have been appeared in earlier works based on the

PRACTICAL ROUTE TO A β-KETOPHOSPHONATE, A KEY INTERMEDIATE FOR THE TOTAL SYNTHESIS OF 20(S)-CPT AND RELATED ANALOGUES

As part of a program for the total synthesis of pentacyclic alkaloids, we were interested in the 20(S)-camptothecin series, such as 20(S)-camptothecin (A), 20(S)-9-nitrocamptothecin (B) and 20(S)10-hydroxycamptothecin (C)I, in which the @ketophosphonate (8) had been established as a key intermediate in the synthesis of these compounds. Ciufolini and Roschanger obtained this compound from propionanilide in 43% overall yield? while Boger and Hong has prepared it from o-amino-benzaldehyde in 47% overall yield.3 Although both yields are

3-Bromomethyl-3-ethyl-3,4,6,7,8,8a-hexahydro-1H-pyrrolo[2,1 -c][1,4]-oxazine-1,4-dione

In the title compound, C10H14BrNO3, the six-membered lactone ring is in a boat conformation, with the two carbonyl groups cis to one another across the boat basal plane. C-H...O hydrogen bonds and weak C-H...Br interactions stabilize the crystal structure.