Palladium-Catalyzed Double C–H Functionalization of Arenes at the Positions <i>ortho</i> and <i>meta</i> to Their Directing Group: Concise Synthesis of Benzocyclobutenes
作者:Takeshi Nanjo、Chihiro Tsukano、Yoshiji Takemoto
DOI:10.1248/cpb.c16-00439
日期:——
The synthesis of benzocyclobutenes from simple arenes bearing a directing group was investigated via the palladium-catalyzed cyclization of norbornene derivatives. This approach allowed for the facile construction of benzocyclobutenes along with the double functionalization of the C–H bonds at the positions ortho and meta to the directing group. This result shows that the key palladacyclopentene intermediate in the Catellani reaction can be prepared by the directed double ortho C–H activation of the substrate. The results of this study also revealed that the combination of an N-protected amino acid with benzoquinone (BQ) was effective for this transformation.
C(aryl)–C(═O) bonds of aryl amides can be activated and added across alkenes with the aid of a nickel catalyst. This 1,2-carboaminocarbonylation reaction enables the dicarbofunctionalization of alkenes with an atom economy of 100%.
Highly asymmetric enzymatic hydrolysis and transesterification of meso-biscacetoxymethyl)- and bis(hydroxymethyl)cyclopentane derivatives: an insight into the active site model of Rhizopus Delemar lipase
作者:Masakazu Tanaka、Miki Yoshioka、Kiyoshi Sakai
DOI:10.1016/s0957-4166(00)80143-3
日期:1993.5
% ee. In explanation of these high enantioselectivities of RDL, the simple box-type active site model of enzyme was tentatively proposed. On the other hand, PFL-catalysed transesterification of meso-bis-(hydroxymethyl) cyclopentane (6) afforded (+)-16 of >99 % ee. The obtained (+) and (−)-16 were converted into the natural carbocyclicnucleoside (−)-aristeromycin (25), respectively.
Practical enzymatic procedure for the synthesis of (–)-aristeromycin
作者:Masakazu Tanaka、Miki Yoshioka、Kiyoshi Sakai
DOI:10.1039/c39920001454
日期:——
Pseudomonas fluoresecens lipase (PFL)-catalysed asymmetric hydrolysis or transesterification of meso-compounds has been used in the synthesis of (–)-aristeromycin 1.
One-Pot Rhodium(I)-Catalyzed Hydroboration of Alkenes: Radical Conjugate Addition
作者:Philippe Renaud、Cyril Ollivier、Valéry Weber
DOI:10.1021/jo034515v
日期:2003.7.1
B-Alkylcatecholboranes, prepared by rhodium(I)-catalyzed hydroboration of alkenes, are suitable radical precursors for conjugate addition to activated olefins. This procedure proved to be particularly useful for the control of the regio- and chemoselectivity of such tandem processes. Enantioselective hydroboration has also been successfully coupled with radical chain reaction in a one-pot process.