Diastereoselective protocols for the synthesis of 2,3-trans- and 2,3-cis-6-methoxy-morpholine-2-carboxylic acid derivatives.

Two diastereoselective and straightforward protocols for the high-yielding synthesis of 2,3-trans- and 2,3-cis-6-methoxy-3-substituted morpholine-2-carboxylic esters were realized in few steps, through the condensation between 5,6-diethoxy-5,6-dimethyl-1,4-dioxan-2-one and an appropriate imine, which is the key reaction to control the C2-C3 relative stereochemistry, followed by a methanolysis/ring-closure tandem reaction sequence. In particular, 2,3-trans-morpholines derive from the R*,S*-product of the acid condensation of N-functionalized alkylimines with the silylketene acetal of the above lactone, whereas 2,3-cis-morpholines derive from the R*,R*-product of basic condensation of an N-tosylimines with the lactone.

Effects of gravity on proliferation and differentiation of adipose tissue-derived stem cells.

Recent studies have demonstrated that culturing stem cells under altered gravity conditions modulates their proliferation and differentiation. In the current study we focused on osteogenesis. In an attempt to induce high proliferation rates and low differentiation of adipose tissue-derived stem cells (AT-MSCs), we exposed them to simulated microgravity (sim-microg) and hypergravity.