Naturally occurring terpenes constitute one of the largest groups of natural products with complicated and variable structures, and a great number of important biological activities. The 2-methyl-D-erythritol 4-phosphate (MEP) pathway is a newly found and established biosynthetic route for terpenoids, and all the enzymes involved in this pathway can be used as targets for the screening of antibiotics. Progress in chemical and enzymatic preparation of the key intermediates in this pathway is reviewed with the emphasis on the synthesis of 1-deoxy-D-xylulose 5-phosphate and 2-methyl-D-erythritol 4-phosphate with isotope labels.

D-Glyceraldehyde 3-phosphate (=D-GAP; 2) was prepared by an improved chemical method (Scheme 2), and it was then employed to synthesize 1-deoxy-D-xylulose 5-phosphate (=DXP; 3) which is enzymatically one of the key intermediates in the MEP (4) terpenoid biosynthetic pathway (Scheme 1). The recombinant DXP synthase of Rhodobacter capsulatus was used to catalyze the condensation of D-glyceraldehyde 3-phosphate (2) and pyruvate (=2-oxopropanoate; 1) to produce the sugar phosphate 3 (Scheme 2). The simple two-step chemoenzymatic route described affords DXP (3) with more than 70% overall yield and higher than 95% purity. The procedure may also be used for the synthesis of isotope-labeled DXP (3) by using isotope-labeled pyruvate.

Two new nitrone alkaloids were isolated from the whole plant of Huperzia serrata (Thunb.) Trev. They are both phlegmarine-type lycopodium alkaloids with a nitrone moiety. Their structures were elucidated on the basis of spectral evidences, and their configurations were established on the basis of optical rotation, CD, and NOESY-NMR data.