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. Author manuscript; available in PMC: 2010 Feb 11.
Published in final edited form as: J Am Chem Soc. 2009 Feb 11;131(5):1947–1957. doi: 10.1021/ja8079548

Table 1.

Intermolecular Diels–Alder Reactions Involving Oxazolidinone Dienophiles.

Entry Reacting partners Conditions Major product exo/endoa Yield
1b 1a + 3* 1.4 equiv. Me2AlCl, CH2Cl2, −40 °C graphic file with name nihms-89481-t0005.jpg 1:5 50%
2c 1b + 3* graphic file with name nihms-89481-t0006.jpg > 20:1 58%
3d 1c + 3* graphic file with name nihms-89481-t0007.jpg > 20:1 65%
4e 2a + 4 graphic file with name nihms-89481-t0008.jpgf 1:20 78%
5 2a + 3 graphic file with name nihms-89481-t0009.jpg > 20:1 62%
6 2b + 3 graphic file with name nihms-89481-t0010.jpg > 20:1 89%
7 2c + 3 graphic file with name nihms-89481-t0011.jpg > 20:1 80%
8 2d + 3* graphic file with name nihms-89481-t0012.jpg > 20:1 48%
9 1a + 5 0.2−0.3 equiv. Me2AlCl, CH2Cl2, RT graphic file with name nihms-89481-t0013.jpg 1:4 15% exo 62% endo
10c 1b + 6 graphic file with name nihms-89481-t0014.jpg 1:10 4% exo 40% endo
11c 1b + 5 graphic file with name nihms-89481-t0015.jpg 11: (1:1.5:0.4)g 78% exo
a

By 400 MHz 1H NMR of the product mixture after aqueous workup.

b

ref. 20.

c

1b used as an inseparable isomeric mixture with (Z,E):(E,E) = 3:1. Reaction of only the major isomer was observed unless otherwise stated.

d

1c used as a mixture with (Z,E):(E,E) = 5:1. Only reaction from the major isomer was observed.

e

At −100 °C.

f

Product of protodesilylation of the primary, endo cycloadduct, epimerized at C5, was isolated after chromatographic purification over silica gel.

g

Four sets of signals were observed by 1H NMR of the crude mixture. Two of the adducts were assigned as exo-17 and its C-5 epimer. The other two, minor adducts were tentatively assigned as the corresponding endo isomers.