4 aromatic protons Can we use 2D to assign this spectrum? Structure first determined by Woodward in 1948 (without NMR!)

CH 2 Identify CH, CH 2 and CH 3 peaks on HSQC (use DEPT if necessary) HSQC

2223 H-22 is a good place to start COSY

Transfer this information to the HSQC spectrum ? H-12 can be tentatively identified from C and H shifts HSQC

We can identify 11 as a CH 2 and 13 as a CH from the HSQC H-8 can distinguished from H-14 by the doublet multiplicity and shift correlation is weak, but is seen on one side of the diagonal , 14 COSY

Note that have a number of “dead ends” as far as COSY is concerned 14 HSQC

The protons at C-15 can be identified by their correlation to H-14 COSY

15 16 Having identified the C-15 protons, we can now see the correlation to H-16 gem COSY

This leaves 3 CH 2 s, at C-17, C-18 and C HSQC

The C-20 protons can be identified as a pair of coupled (from COSY) doublets, not coupled to anything else HSQC

The CH 2 s at C-17 and C- 18 are left. The HSQC shows an overlapping CH 2 at 1.94 ppm. The chemical shift indicates that this must be the C-17 CH 2. The CH 2 at 2.92 and 3.35 ppm must be C (diagonal) 18 COSY

All protonated carbons have now been assigned HSQC

C-10 H-12 H-11axH-11eq We can now use HMBC to assign the non-protonated carbons (and confirm other assignments, if necessary) HMBC

C-7 H-1 CH H-15 H-8 C-18 C-20 H-18 H-20 2 bond C-7 to H-16 correlation not observed? HMBC

COSY TOCSY (diagonal) 14

NOESY Avance 300 Degassed sample Degassing removes oxygen (paramagnetic) from the sample which would otherwise provide alternate relaxation pathways. gem NOESY

CH H-15 H-13 H-11 H-8 H-18 N-9 N-19 H-18 H N-HMBC 15 N spectroscopy is very difficult! However, we can measure 15 N shifts and determine the location of the nitrogens with HMBC (AMX 500, 10 mg sample, overnight)