Michael Cholbi thinks he has some:
First, the lie is not meant to advance the happiness either of the liar or of the potential murder victim, but to thwart the abuse of the victim’s autonomy that her murder would represent. Hence, if lying to the murderer is manipulation at all, it is manipulation in the service of the would-be victim’s autonomy, a central Kantian value. Second, while Kantian ethics prioritizes the value of autonomous rational agency over happiness, it does not follow from this that we are obligated to honor another agent’s autonomous choices no matter the ends that a given exercise of autonomy is meant to serve.
See his whole argument at PEA Soup.
Here’s one interesting sidebar on the way to his overall conclusions:
Kantian Symmetry Thesis: Any morally permissible act performed by agent A in which A is also the act’s beneficiary is also permissible if another agent B (relevantly similar to A) is the beneficiary of A’s act instead.
We see throughout Kant’s casuistry implicit appeals to this thesis: Suicide, Kant thought, is wrong for just the same reasons (and in just the same circumstances) that homicide is wrong. Similarly, in Kant’s sexual ethics (not that we should accept much of it of course!) acts that treat another’s sexuality as a mere tool of one’s happiness (rape) are wrong in the same way that acts that treat one’s own sexuality as a tool of one’s own happiness (masturbation) are wrong. In other words, Kant did not think that there exists a special moral relationship to oneself such that the obligations one bears vis-a-vis oneself are importantly distinct from those one bears toward other agents. (This is a way in which Kant was not a ‘liberal,’ since one important feature of liberalism has been the idea of a domain of self-regarding behavior that is governed by different norms from the domain of other-regarding behavior).