Nature Chemistry 1, 63–68 (2009); published online 19 March 2009; corrected after print 6 April 2009.

In the version of this Article originally published, the stereochemical descriptors given in the Methods section for compounds 23, 25, 27 and 29 were incorrect; they have now been corrected in the HTML and PDF versions, and should have appeared as shown below.

23 (S)-3-(((S)-7,7-Dimethyl-3-(2-methylbut-3-en-2-yl)-2-oxo-1,2,3,7-tetrahydropyrano[2,3-g]indol-3-yl)methyl)-2,3,6,7-tetrahydropyrrolo[1,2-a]pyrazine-1,4-dione

25 (S)-3-(((R)-7,7-Dimethyl-3-(2-methylbut-3-en-2-yl)-2-oxo-1,2,3,7-tetrahydropyrano[2,3-g]indol-3-yl)methyl)-2,3,6,7-tetrahydropyrrolo[1,2-a]pyrazine-1,4-dione

27 (R)-3-(((S)-7,7-Dimethyl-3-(2-methylbut-3-en-2-yl)-2-oxo-1,2,3,7-tetrahydropyrano[2,3-g]indol-3-yl)methyl)-2,3,6,7-tetrahydropyrrolo[1,2-a]pyrazine-1,4-dione

29 (R)-3-(((R)-7,7-Dimethyl-3-(2-methylbut-3-en-2-yl)-2-oxo-1,2,3,7-tetrahydropyrano[2,3-g]indol-3-yl)methyl)-2,3,6,7-tetrahydropyrrolo[1,2-a]pyrazine-1,4-dione

An in-house error meant the graphical abstract on the Table of Contents page was missing a double bond in (+)-versicolamide B; this has now been corrected in the HTML and PDF versions, and should have appeared as shown above.