PLT ex gq.plt

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1 Problem R-06 ( 1 18 O ) 200 Mz 1 NMR spectrum in l Source: Yuntao Song, huck eap-burke (Reich digitized hard copy 28-10) g z O O Ph O xchange with 2 O B Problem R-06 ( 1 18 O ) 7 Mz 1 NMR spectrum in l Source: Yuntao Song (huck eap-sb) PT-1 Normal

2 Problem R-06 ( 1 18 O ). etermine the structure (or part structure) of R-06 from the 1 and 1 NMR spectra provided. The compound contains a Ph- 2 -O- 2 -O- group. (a) B (b) Interpret the 1 NMR spectrum. Use the Normal and PT-1 spectra to help in the analysis. Identify what kind of carbon each signal corresponds to and write possible part structures (you may wish to examine all the data before completing this section). Problem R-06 ( 1 18 O ) 7 Mz 1 NMR spectrum in l Source: Yuntao Song (huck eap-sb) PT-1 Normal Type of (e.g. sp 2 ) and/or part structures (e.g. N- 2 )

3 (c) When 2 O was added to the sample, the signal B disappeared and became a clean triplet. What does this tell you about these peaks? (d) What can you learn from the signals and (part structures)? (e) nalyze the 1-proton multiplet at δ.9 (shown below). raw a coupling tree on the multiplet below, and report coupling constants (in the standard form: e.g., δ.9, tq, J = 12, 4 z, 1). Show any part structure you could obtain from the signal. You may use first-order analysis. (f) nalyze the signals labeled (two protons at δ.), reproduced below. Show couplings with (coupling tree) and report J values and a part structure. You may use first order analysis (g) ssign the signals and and explain their appearance. What kind of multiplets are these? o an accurate calculation of the chemical shifts and couplings for multiplet (frequencies are given on the spectrum). (h) raw the structure of R-06. If more than one structure is possible, show them, and circle the one you think fits the data best and give your reasons for choosing it. Place labels on the protons (, B, etc) to identity their NMR signals.

4 Problem R-06 ( 1 18 O ) 200 Mz 1 NMR spectrum in l Source: Yuntao Song (huck eap-burke) z xchange with 2 O B

5 Problem R-06 ( 1 18 O ). etermine the structure (or part structure) of R-06 from the 1 and 1 NMR spectra provided. The compound contains a Ph- 2 -O- 2 -O- group. 1 (a) B Ph has 4 B, thus one double bond/ring in rest of molecule (b) Interpret the 1 NMR spectrum. Use the Normal and PT-1 spectra to help in the analysis. Identify what kind of carbon each signal corresponds to and write possible part structures (you may wish to examine all the data before completing this section). Problem R-06 ( 1 18 O ) 7 Mz 1 NMR spectrum in l Source: Yuntao Song (huck eap-sb) PT-1 Normal Type of (e.g. sp 2 ) and/or part structures (e.g. N- 2 ) sp 2 (p Ph-) O sp 2 (2) (m or o Ph-) O sp 2 (2) (m or o Ph-) O sp 2 (probably = 2 ) 9.8 O- 2 -O (possibly = 2 ) 17.8 sp 2 (ipso Ph carbon) = Only 17 - protons apparent in -1, so most be O

6 (c) When 2 O was added to the sample, the signal B disappeared and became a clean triplet. What does this tell you about these peaks? O B O B B is an O signal, and it is coupled to a coupled to two other protons 2 or Most common error - failure to consider second structure (d) What can you learn from the signals and (part structures)? is probably a - group, is coupled to it, and to one additional proton : 1.18, d, J 7 z :.69, pentet, J= 6 z (e) nalyze the 1-proton multiplet at δ.9 (shown below). raw a coupling tree on the multiplet below, and report coupling constants (in the standard form: e.g., δ.9, tq, J = 12, 4 z, 1). Show any part structure you could obtain from the signal. You may use first-order analysis. ( ) δ.89, ddd, J = 17, 10, 7 z This is a very characteristic multiplet of a proton coupled cis (10 z) and trans (17 z) across adouble bond, plus one additional coupling (7 z) (f) nalyze the signals labeled (two protons at δ.), reproduced below. Show couplings with (coupling tree) and report J values and a part structure. You may use first order analysis. are the two terminal = 2 protons, one coupled cis (10 z), the other trans (17 z) the additional splittings are the 2 J between them, and a long range coupling.22, dt, J= 10, 1. or ddd, J= 10, 1., 1.6, dt, J = 16,, (g) ssign the signals and and explain their appearance. What kind of multiplets are these? o an accurate calculation of the chemical shifts and couplings for multiplet (frequencies are given on the spectrum). 8 Both and are B quartets, corresponding to the diastereotopic O- 2 -O () and Ph- 2 -O () groups of the BOM protecting group. Molecule must have an asymmetric center. J B = 11.4 z = 928. z ν B = 10.7 z ν = 92.0 ν B = 9.6 δ = 4.62 δ B = for no δ -2 for not diving υ B by 2 (h) raw the structure of R-06. If more than one structure is possible, show them, and circle the one you think fits the data best and give your reasons for choosing it. Place labels on the protons (, B, etc) to identity their NMR signals. O O O O Ph O O Ph O O Ph O points for assignment + about 10 other structures Stereochestry not easily assignable

7 Problem R-06 ( 1 18 O ) 200 Mz 1 NMR spectrum in l Source: Yuntao Song (huck eap-sb) O O Ph O z xchange with 2 O B