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Organic syntheses vol 58 - Sheppard W.A.

Sheppard W.A., Buchi G.H. Organic syntheses vol 58 - Wiley, 1978. - 123 p.
Download (direct link): organicsynthesesvol581978.pdf
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78
ORGANIC SYNTHESES—VOL. 58
TABLE I
Preparation op Tertiary- and Secondary-Alkyl Fluorides from Alcohols with Hydrogen Fluoride-Pyridine Reagent
Alcohol Temp- erature Reaction Time (hours) Alkyl Fluoride b.p. (m.p.) Yield (%)
Isopropyl 50 3.0 Isopropyl -9 to -7 30
sec-Butyl 20 3.0 sec-Butyl 25-26 70
tert-Butyl 0 1.0 (erf-Butyl 12 50
3-Ethyl-3-pentyl 0 0.5 3-Ethyl-3-pentyl 30-33 (60 mm.) 95
3-Methyl-3-heptyl -70 0.5 3-Methyl-3-heptyl 35 (40 mm.) 85
3-Methyl-4-heptyl 0 2.0 3-Methyl-4-heptyl 35
Cyclohexyl 20 2.0 Cyclohexyl fluoride 100-102 99
2-Norbornyl 20 1.0 2-Norbornyl (56-59) 95
2-Adamantyl 20 0.5 2-Adamantyl (254-255) 98
a-Phenylethyl 20 0.5 a-Phenylethyl 46 (15 mm.) 65
HF-pyridine reagent, however, can also be used for the hy-
drofluorination of alkenes,7 alkynes,7 cyclopropanes,7 and diazo compounds,8 the halofluorination of alkenes,9 the preparation of fluoroformates from carbamates,10 the preparation of a-fluorocarboxylic acids from a-amino acids,11 and as a deprotecting reagent in peptide chemistry.12 Examples of the hydrofluorination of alkenes with HF-pyridine are given in Table II.
TABLE II
Hydrofluorination of Alkenes with Hydrogen Fluoride-Pyridine
Reagent
Reaction
Temp- Yield
Alkene erature Product b.p. (m.p.) (%)
Propene 20 Isopropyl fluoride -11 to -9 35
Cyclopropane 20 Propyl fluoride -3 to -1 75
2-Butene 0 sec-Butyl fluoride 24-25 40
2-MethyIpropene 0 tert-Butyl fluoride 11-13 60
Cyclopentene 0 Cyclopentyl fluoride 51-52 (200 mm.) 65
Cyclohexene 0 Cyclohexyl fluoride 102-104 80
Cycloheptene 0 Cycloheptyl fluoride 70-71 (200 mm.) 90
Norbornene 0 2-Norbornyl fluoride (56-59) 65
1-Hexyne 0 2,2-Difluorohexane 85-87 70
3-Hexyne 0 3,3 -Difluorohexane 84-86 75
7-KETOESTERS FROM ALDEHYDES VIA DIETHYL ACYLSUCCINATES 79
1. Institute of Hydrocarbon Chemistry, Department of Chemistry, University of Southern California, Los Angeles, California 90007.
2. G. A. Olah and S. J. Kuhn, Org. Syn., Coll. Vol. 5, 66 (1973); Ñ. M. Sharts and W. A. Sheppard, Org. React., 21, 192, 220-223 (1974).
3. R. C. Fort and P. v. R. Schleyer, J. Org. Chem., 30, 789 (1965).
4. K. S. Bhandari and R. E. Pincock, Synthesis, 655 (1977).
5. G. A. Olah, M. Nojima, and I. Kerekes, Synthesis, 786 (1973).
6. W. J. Middleton and E. M. Bingham, Org. Syn., 57, 50, 72 (1977).
7. G. A. Olah, M. Nojima, and I. Kerekes, Synthesis, 779 (1973).
8. G. A. Olah and J. Welch, Synthesis, 896 (1974).
9. G. A. Olah, M. Nojima, and I. Kerekes, Synthesis, 780 (1973).
10. G. A. Olah and J. Welch, Synthesis, 654 (1974).
11. G. A. Olah and J. Welch, Synthesis, 652 (1974).
12. S. Matsuura, Ñ. H. Niu, and J. S. Cohen, Chem. Commun., 451 (1976).
Chemical Abstracts Nomenclature (Collective Index Number; Registry Numbers)
Adamantane, 1-fluoro- (8); Tricyclo[3.3.1.13'7]decane, 1-fluoro-(9); (768-92-3)
Hydrogen fluoride: Hydrofluoric acid (8,9); (7664-39-3)
Pyridine (8,9); (110-86-1)
1-Adamantanol (8); Tricyclo[3.3.1.13,7]decan-l-ol (9); (768-95-6)
7-KETOESTERS FROM ALDEHYDES VIA DIETHYL ACYLSUCCINATES: 4-OXOHEXANOIC ACID ETHYL ESTER
Appendix
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î
A.
benzoyl peroxide hv, reflux
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2
Submitted by Pius A. Wehrli and Vera Chu1
Cheeked by William B. Farnham and William A. Sheppard
80
ORGANIC SYNTHESES—VOL. 58
1. Procedure
A. Diethyl propionylsuccinate (1). A solution of 412 g. (2.4 mole) of diethyl maleate (Note 1), 278 g. (4.8 mole) of freshly distilled propionaldehyde (Note 2), and 1.2 g. (0.0048 mole) of benzoyl peroxide in a normal 2-1. Pyrex flask is heated under reflux while undergoing irradiation with an ultraviolet lamp (Note 3). The initial reflux temperature is 60°. After 2 hours another 1.2 g. (0.0048 mole) of benzoyl peroxide is added. Strong reflux and irradiation are maintained throughout the entire reaction period. After 18 hours’ total time, the internal pot temperature reaches 68°. At this point the last 1.2 g. (0.0048 mole) of benzoyl peroxide is added, and the reaction is continued for a total of 30 hours, at which time the pot temperature reaches 74.5°. The reflux condenser is then replaced by a distillation head. The excess propionaldehyde (119 g.) is distilled under atmospheric pressure, b.p. 48-49°. Succinate 1 is distilled under reduced pressure. The main fraction, b.p. 145-151.5° (15-16 mm), provides 417-449 g. (75-81%) of product having sufficient purity for use in the next step (Note 4).
B. 4-Oxohexanoic acid ethyl ester (2). A 1-1., three-necked, round-bottomed flask is equipped with a mechanical stirrer, thermometer, and Claisen condenser connected to a gas-measuring device (Note 5). The flask is charged with 276 g. (1.2 mole) of succinate 1 and 74.1 g. (1.2 mole) of boric acid (Note 6). The initially heterogeneous mixture is stirred and immersed in a 150° oil bath. Within 1 hour 36 g. of distillate (mainly ethanol) and approximately 2.3 1. of gas collect. As the temperature is raised to 170°, the rate of carbon dioxide evolution increases, a total of
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