23 December 2008

Not so trivial typos 1

I anticipate that I'll make quite a large number of typographical errors whilst blogging but I'll try to make sure that they aren't as a egregious as Actavis UK Ltd v Janssen Pharmaceutica NV [2008] EWHC 1422: the offending passage is reproduced below.

"15 This case concerns the stereochemistry of compounds with more than one chiral centre. In theory a structure with a number of chiral centres, (say N), will exist as 2N stereoisomers. So a structure such as that with which we are concerned in this case, with four chiral centres, could in theory have 16 stereoisomers. These stereoisomers consist of pairs of enantiomers, and there will be half of 2N, or 2(N-1) of these pairs. This is not always true, however, because in symmetrical molecules some of the stereoisomers will be the same.

16 A simple example is tartaric acid which has two chiral centres, and would therefore be expected to have four stereoisomers. In fact it has only three. In the diagram below enantiomers C and D are identical, because rotating one about the vertical axis makes it so:



17 Compunds which have chiral centres but which are in fact achiral are called meso compounds."


The typo is trivial - it is A and B, rather than C and D, that are identical - but it makes the difference between sense and nonsense; right and wrong.

Reading the passage more closely suggests a lack of understanding of Fisher projection by the author (although that isn't clear from the thickie-pedia explanation) rather than a simple typo. There is also a typo at the start of paragraph 17 but this has no effect upon what is being conveyed.

For a legal analysis of the patent here's a link to "Patent claims can't be interpreted by analogy" from the IPKat.

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