Synthesis of Retigeranic Acid

C25H38O2

Principal investigator	Leo A. Paquette
Publication year	1987
Synthesis type	Total
Number of steps	29 (3 parts)
References	J. Org. Chem. 1987, 52, 2960. J. Am. Chem. Soc. 1984, 106, 6690.

Part 1 of 3

KH, NaH

PhMe

Reflux, 20 h, 66%

O3
Me2S

MeOH

-78 °C to RT, 79%

NaH

PhMe

Reflux, 18.5 h, 66%

See the Aldol Condensation

LiI.3H2O

DMF

Reflux, 18 h, 85%

See the Krapcho Decarboxylation

CuBr.Me2S

THF, Me2S

-78 to 0 °C, 24 h

See the Michael Addition

HCl

Acetone, H2O

RT, 3 d, 72% (2 steps)

See the Aldol Addition

ClC(S)O(p-MePh)

Pyr

RT, ON, 73%

24 mmHg

180 °C, 60 min, 99%

See the Chugaev Elimination

NH2NH2.H2O, K2CO3

Diethylene glycol

150 to 200 °C, 7 h, 72%

See the Wolff-Kishner Reduction

Na2CrO4

Ac2O, AcOH

0 °C to RT, 24 h, 64%

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Part 2 of 3

i-Bu2AlH

100%

n-Bu3SnCH2I, KH

n-BuLi

75% (2 steps)

See the Wittig Rearrangement-[2,3]

O3
Me2S

70%

TBSCl, Imidazole

DMF

85%

i-Bu2AlH

100%

POCl3

Pyr

40-45 °C, 75%

3,5-Dimethylpyrazole, CrO3

CH2Cl2

49%

CuBr.Me2S, VinylMgBr

50%

See the Michael Addition

"Also isolate was the C3-epimer (15 % yield)."

NH2NH2.H2O, K2CO3

Diethylene glycol

190 °C, 73%

See the Wolff-Kishner Reduction

Ph3P, DEAD, ZnBr2

THF

RT, 91%

See the Mitsunobu Reaction

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Part 3 of 3

Mg

																	Et2O															

								Reflux, 																13%
							
								See the Michael Addition
							
								"Also isolated was the C3-epimer (40 % yield)."