A research program devoted to the development of new methods for carbohydrate synthesis and studies of their biological activities is proposed. Carbohydrates and glycoconjugates are mediators of many medicinally important physiological processes, such as cancer metastasis, inflammation, anticoagulation and bacterial infection. Chemical syntheses of oligosaccharides are crucial for providing pure samples for glycobiological studies. Traditional carbohydrate synthesis is a time-consuming process due to tedious protective group manipulation and intermediate purification. Two novel one-pot approaches where multiple glycosylation reactions can be carried out in a single reaction flask without separation of synthetic intermediates are proposed. The first proposed method utilizes glycosyl building blocks with anomeric activities tuned through aglycons with various electron withdrawing power and building blocks with multiple levels of reactivity can be derived from a common intermediate. This will greatly expand the reactivity window and reduce the time and efforts for building block preparation. The second proposed strategy is based on pre-activation of glycosyl donors in the absence of acceptors, which can be carried out iteratively independent of donor anomeric reactivities. The iterative one-pot method represents a general and powerful approach, which can potentially become a fully automated solution-phase based carbohydrate synthesis method. Mechanisms of the two proposed methods will be investigated and the lessons learned will be applied for further development. To demonstrate the broad applicability of proposed strategies, a complex type bi-antennary dodecasaccharide and a series of sulfated chitosanoligosaccharides will be synthesized. The anticoagulant properties of the sulfated chitosanoligosaccharides will be determined for better understanding of their structure-activity relationship and development of more potent anticoagulants.