Quantitation in the regioselectivity of acylation of glycosyl diglycerides: total synthesis of a Streptococcus pneumoniae α-glucosyl diglycerideElectronic supplementary information (ESI) available. See DOI: 10.1039/c6cc09584d

The fidelity of acylation regioselectivity in the synthesis of mixed glycosyl diacylglycerols can be accurately measured by quantitative 13 C NMR spectroscopy using a 1- 13 C-labelled fatty acid and a paramagnetic relaxation enhancement agent. Exquisite regioselectivity is achieved using a stepwise acylation/substitution of a glycosyl β-bromohydrin, which is applied to the total synthesis of Streptococcus pneumoniae Glc-DAG-s2. Regioselective fidelity of acylation of glycosyl diacylglycerols can be monitored by use of isotope-labelled fatty acids and quantitative 13 C NMR spectroscopy.