Synthesis of phthalides
A surprisingly facile conversion of 2-formyl-arylketones into 3-substituted phthalides generally proceeds smoothly in DMSO, either in a Cannizarro-Tishchenko-type reaction under nucleophile catalysis (NaCN) or under photochemical conditions (DMSO, 350 nm).
D. C. Gerbino, D. Augner, N. Slavoy, H.-G. Schmalz, Org. Lett., 2012, 14, 2338-2341.
A palladium-catalyzed arylation of aldehydes with organoboronic acids gave 3-arylphthalides in good to excellent yields with high substrate tolerance in the presence of a thioether-imidazolinium carbene ligand.
M. Kuriyama, N. Ishiyama, R. Shimazawa, R. Shirai, O. Onomura, J. Org. Chem., 2009, 74, 9210-9213.
A new diamine ligand for Ru-catalyzed asymmetric transfer hydrogenation (ATH) enabled a highly enantioselective reduction of 2-acylarylcarboxylates. Subsequent in situ lactonization under aqueous conditions provided efficient access to a various 3-substituted phthalides in enantiomerically pure form.
B. Zhang, M.-H. Xu, G.-Q. Lin, Org. Lett., 2009, 11, 4712-4715.
Cobalt-catalyzed intramolecular hydroacylations of 2-acylbenzaldehydes and 2-alkenylbenzaldehydes afford phthalide and indanone derivatives, respectively, in good yields with high enantioselectivities in the presence of chiral diphoshines.
J. Yang, N. Yoshikai, J. Am. Chem. Soc., 2014, 136, 16748-16749.
Pd catalysis enables an efficient synthesis of a broad range of isobenzofuran-1(3H)-ones from o-bromobenzyl tertiary/secondary/primary alcohols.
L. Mahendar, G. Satyanarayana, J. Org. Chem., 2016, 81, 7685-7691.
An efficient domino one-pot strategy for the synthesis of isobenzofuran-1(3H)-ones includes [Cu]-catalyzed intermolecular cyanation of o-bromobenzyl alcohols, in situ intramolecular nucleophilic attack and hydrolysis. This reaction can successfully be carried out under environmentally benign conditions, using water as sole green solvent.
L. Mahendar, G. Satyanarayana, J. Org. Chem., 2015, 80, 7089-7098.
A modified Julia olefination enables a highly stereoselective synthesis of exo-enol esters from cyclic anhydrides. A subsequent one-pot Smiles rearrangement gives a straightforward access to exo-enol lactones. Furthermore, the reaction was extended to semistabilized sulfones and applied to the synthesis of maculalactone B.
N. Dussart, H. V. Trinh, D. Gueyrard, Org. Lett., 2016, 18, 4790-4793.
A highly efficient palladium(0)-catalyzed strategy for the synthesis of isocoumarins involves cyclization with incorporation of tert-butyl isocyanide followed by simple acid hydrolysis to provide valuable lactones in good yields. The methodology is tolerant of a wide range of substrates and applicable to library synthesis.
X.-D. Fei, Z.-Y. Ge, T. Tang, Y.-M. Zhu, S.-J. Ji, J. Org. Chem., 2012, 77, 10321-10328.