6123
Communications t o the Editor a common aldehyde, benzaldehyde, to minimize the changes in reaction variables, we have found our observations to be general. For example, the (Z)-dibutylboron enolate derived from 3-pentanone affords cleanly the erythro-aldol adducts with n-butyraldehyde, isobutyraldehyde, crotonaldehyde, and methacr~lein.'~ The generality of these reactions and the application of chiral boron enolates to enantioselective aldol condensations will be reported in due course.
Acknowledgment. This work has been supported by the National Science Foundation.
Scheme I
R R+OH
OEt 3a, R = H (70%) b, R = Me (87%)
2
References and Notes
A
(1) (a) J.-E. Dubois and M. Dubois, Tetrahedron Lett., 4215 (1967); (b) J.-E. Dubois and P. Fellrnann, C.R. Acad. Sci., 274, 1307 (1972); (c) J . I . Dubois and P. Felimann, Tetrahedron Lett., 1225 (1975). (2) (a) W. A. Kleschick, C. T. Buse, and C. H. Heathcock. J. Am. Chem. Soc., 99, 247 (1977); (b) C. T. Buse and C. H. Heathcock, ibid., 99, 8109 (1977). (3) J. Mulzer, J. Segner, and G. Bruntrup, Tetrahedron Lett., 4651 (1977). (4) H. 0. House, D. S. Crumrine, A. Y. Teranishi. and H. D. Olmstead, J. Am. Chem. Soc.. 95, 3310 (1973). (5) (a) J. 0. Thomas, R. Tellgren. and J. Almlof, Acta Crysta//ogr., Sect. 6, 31, 1946 (1975); G. 6.Johansson and 0. Lindqvist, ibid., 32,412 (1976); G. de With, S. Harkema, and G. H. van Hummel, ibid., 32, 1980 (1976); (b) R. G. Vranka and E. L. Amma, J. Am. Cbem. Soc., 89, 3121 (1967); R. L. Gerteis, R. E. Dickerson, and T. L. Brown, Inorg. Cbem., 3,872 (1964); E. Weiss, J. Organornet. Cbem., 2, 314 (1964). (6) Preliminary reports indicate that dialkylaluminum enolates might prove useful in some cases: however, bond length considerations5 render these systems somewhat less attractive: (a) E. A. Jeffery, A. Meisters. and T. Mole, J. Organornet. Chem., 74, 365 (1974); (b) K. Marnoka, S. Hashimoto, *Y. Kitagawa, H. Yamamoto, and H. Nozaki, J. Am. Chem. SOC.,99, 7705 (1977). (7) (a) T. Mukaiyama and T. Inoue, Chem. Lett., 559 (1976); (b) W. Fenzl and R. Koster, Justus Liebigs Ann. Chem., 1322 (1975); the and (Q-enolates (RI = Ph) were reported to undergo stereoselective condensation with CzH5CHO to give 4a and 5a, respectively. (8) (a) For representative B-0 bond lengths, see W. H. Zachariasen, Acta Crystallogr., 16, 385 (1963). (b) For representativeB-C bond lengths, see D. Groves, W. Rhine, andG. D. Stucky. J. Am. Chem. Soc.. 93, 1553(1971); L. S. Bartell and B. L. Carroll, J. Cbem. Phys., 42, 3076 (1965). (9) (a) G. Schmitt and B. Olbertz, J. Organomet. Cbem.. 152, 271 (1978); (b) E. Vedejs, D. A. Engler, and J. E. Telschow. J. Org. Cbem., 43, 188 (1978). (10) To tricyclopentylborane (H. C. Brown and B. C. Subba Rao, J. Am. Chem. SOC.,81, 6423 (1959))(1 equiv) was added with cooling 1 equiv of trifluoromethanesulfonic acid. Short-path distillation afforded 2b in 90% yield, bp 70-72 OC (1.0 mmHg). ( 1 1) Satisfactory spectral and analytical data were obtained on all new compounds. (12) Boron trilfate 2c was generated in situ in the following manner. A mixture of 1 equiv each of thexylborane and cyclopentene in THF (1.0 M) was stirred at -30 'C (1 h), cooled to -78 OC, and quenched with 1 equiv of trifluoromethanesulfonic acid (dropwise). (13) Treatment of tert-butyl thiopropionate with LDA (Et20, -78 "C) affords 2 9 5 % enolate corresponding to 3E in direct analogy to the observation of Ireland.14 (14) R. E. Ireland, R. H. Muelier, and A. K. Willard, J. Am. Chem. SOC.,98,2868 (1976). (15) NOTEADDED IN PROOF. S.Masamune has recently reported qualitatively similar observations with boron enolates: S.Masamune, S. Mori, D. Van Horn, and D. W. Brooks, Tetrahedron Lett., 1665 (1979).
(a
D. A. Evans,* E. Vogel, J. V. Nelson Contribution No. 601 9. Laboratories of Chemistry California Institute of Technology Pasadena, California 91 I25 Receiued May 9, 1979
Annulated Pyranosides as Chiral Synthons for Carbocyclic Systems. Enantiospecific Routes to Both (+ 1- and (-)-Chrysanthemumdicarboxylic Acids from a Single Progenitor Sir:
There is currently considerable interest in the use of carbohydrate derivatives as chiral synthons as may be judged from thc growing number of synthetic accomplishments in recent ycurs.' These accomplishments fall largely into two categories 0002-7863/79/ I501 -61 23$0 I .OO/O
rOTr
4a, R = H (90%) b, R = Me ( 0 % )
5 A
I
R
d, R = Me; R' = CHiCl (92%) e, R = M e ; R' = Me (89%)
'
for which we have suggested' the terms (a) acyclic transfer and ( b ) cyclic transfer to denote the manner in which the carbohydrate moiety has been employed. A third category, (c) transcription, may be recognized'.* which is particularly applicable to carbocyclic compounds, and, in this context, it is noteworthy that Stork's synthesis of the prostaglandins9 is the only instance, to our knowledge, where a carbocyclic natural product has been synthesized from a sugar.I0 In this communication, we introduce the novel concept of annulated pyranosides as chiral synthons for carbocyclic systems, and exemplify the potential of this methodology by outlining the enantiospecific syntheses of (+)- and (-)chrysanthemumdicarboxylic acids (1) from a single precursor, whereby all stereochemical centers of the target are of known, predetermined configuration by "transcription" from the carbohydrate template. A signifcant aspect ofthis work is that i t i7iakr.r procision f o r preparing chrysanthemates with isotopie labels at a cariety of specific sites. In the context of this project, the key structural feature is the gem-dimethylcyclopropane ring, and, of the many routes" l 4 which we and others have developed to cyclopropano-pyranosides, the one chosen for initial study is that summarized in Scheme I . Thus, the photoinduced alkylation of cnone 2 with methanol gave the keto1 3a which was converted into 4a in excellent yield.I3 For the synthesis of 4b, the tcrti>.ryalcohol 3b was obtained in 87% yield by alkylation of 2 with 2-propanol. However, all attemptsi5 to bring about cyclization 3bI6 4b met with abject failure. We next turned our attention to the carboethoxy cyclopro' ~ ~studied pane 7a, first prepared by Meyer zu R e ~ k e n d o r fand further by Attempts to a-methylate 7a were unsuccessful. We therefore examined the reaction of 5 with the
-
0 1979 American Chemical Society
0 I24
Journal of the American Chemical Society
/
101:20
/ September 26, 1979
Scheme I1
/OH
NaOMe-MeOH
ph
(94%)
.CHO
L-y
\
8
I'
9
CH,C=P(Ph)J COOMe
I'll
T
c
w
O
(%%I
o- M
e
10
i
1. MeOH-TsOH (100%) 2. NaIO, ( 8 4 % )
ow&
COOMe 13
COOMe
I
1. MeOH-TsOH ( 9 3 % ) 2. NaIO, ( 9 4 % )
11
I
1. MeOH-NaOMe (100%) 2. Ag,O-NaOH ( 8 9 % )
O
H
C
1
G
\
COOMe
Ag,O-NaOH
l
