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This thesis is concerned with the calculation of fixed moments of theO(a_s^3) heavy flavor contributions to the Wilson coefficients of the structurefunction F_2(x,Q^2) in the limit Q^2 >> m^2, neglecting power corrections. Themassive Wilson coefficients in the asymptotic region are given as convolutionsof massive operator matrix elements (OMEs) and the known light flavor Wilsoncoefficients. The former derive from the twist--2 operators emerging in thelight--cone--expansion and are calculated at the 3--loop level for fixedmoments. We also compute the massive OMEs which are needed to evaluate heavyflavor parton distributions in the variable flavor number scheme to the sameorder. All contributions to the Wilson coefficients and OMEs but the genuineconstant terms at O(a_s^3) of the OMEs are derived in terms of quantities,which are known for general values in the Mellin variable N. For the OMEsA_{Qg}^(3), A_{qg,Q}^(3) and A_{gg,Q}^(3) the moments N = 2 to 10, forA_{Qq}^{(3), PS} to N = 12, and for A_{qq,Q}^{(3), NS}, A_{qq,Q}^{(3), PS},A_{gq,Q}^(3)}to N=14 are computed. These terms contribute to the light flavor'+'-combinations. For the flavor non-singlet terms, we calculate as well theodd moments N=1 to 13, corresponding to the light flavor '-'-combinations. Wealso obtain moments of the terms ~ T_F of the 3-loop anomalous dimensions in anindependent calculation, which agree with results given in the literature. Themathematical structure of the occurring momentum integrals and of the finalresults in terms of harmonic sums is discussed. We study applications of thesame techniques to the polarized and transversity case at the NLO and NNLOlevel as well.

Mellin moments of heavy flavor contributions to F_2(x,Q^2) at NNLO