A simple synthesis of dihydrojasmonea

Tetrahedron Letters,Vol.24,No.5,pp Printed in Creat Britain

A SIMPLE SYNTHESIS

OF DIHYDROJASMONE+

Shing-Hou

It is weil-known proceeds

that acid-catalyzed

with concomitant

mrgration

double bond isomerization precursors

Bromination3

(5 equiv.)

taminated

in a synthesis

of _2 to a mixture

of dihydrojasmone

enone 2 ' in 80% yield.

20 h) of 2 afforded

with another

acetal

1,4-diacetal

hydrolyzed

(0.5 N HCl, EtOH, rt) and the resulting

dioxane

2

were treated with aikali

ketone _65.

5 was converted

We anticipated

its hydrolysis

ketones

(2 equiv.)

However,

and pyridine

mixture

toluene

the product

The by-product

Thus, the mixture

containing

to give rise to a separable

the well-known

0

_

+

_

& ti ;R=+;;5111 _ 49 f Dedicated to Professor Yau-Tang Lin on the occasion of his 70th birthday. * Present Address: Organic Chemicals Division, SCM Corporation, P. 0. Box 389, 32201 USA Jacksonville, Florida

439

was

-8 and

and indeed

for 18 h.

1 R=H

? R=Br 2 - R=CCH3

was con-

undecan-2,5-

of dihydrojasmone

with cont. HCl in benzene

or

of acetals was

of _ 6 could be made reversible,

into dione z in 75% yieid when refluxed

of

A4 gave the bromo enone

to separate.

product 5 5 .

that the formation

the utility

(ethylene glycol,

s5, as expected.

identified

vaiuable

which was then stored at room temperature

Acetalization

eventually

enones undergo

-S2.

cupric bromide6

(2U-50%) which was difficult

as 2 through

reports

1.5 h) of 3-undecen-5-one

in a green mixture

ketones

should be 1,4-diacetals,

This communication

of anhydrous

by acid hydrolysis

cl,&unsaturated

If acyclic y-alkoxy

the product

acetalization,

at -30° resulted

(14 h) to give y-methoxy

of alicyclic

of the double bond'.

and cyclopentenones.

process

Addition

in MeOH'

TsOH,

acetalization

(1 equiv. NBS, Ccl4 reflux,

(95% yield).

benzene,

during

to 1,4-diketones

such an acetalization

dione -7

Liu*

Life Sciences Division, SRI International Menlo Park, California 94025 USA Acetalization of a y-substituted o,@unsaturated ketone, followed gave a cyclopentenone.

Abstract:

1'

0040-4039/83/050439-02$02.00/O 01983 Perqamon Press Ltd.

439-440,1983

440

Acetalization presumably

of the bromo enone -2 afforded

from displacement

and acetalization

of the intermediate

acid and cont. hydrochloric -1.

of bromide

acid

by

ethylene

ketone -6

aldol condensation

Similarly,

The facile formation transformation

_g8 was prepared

of 2,3-disubstituted

may find use in the syntheses

Acknowledgement:

The author

dihydrojasmone

discussions

and Takeshi

-8 is rarely

derivatives

of heterocyclic

yield

and was isolable.

from 3-decen-5-one

thanks Drs. J. M. Muchowski,

5 which

in a solution

-8 in 45% overall

by GC analysis

dioxane

acetal

followed by a Michael-type

(1:l) to give dihydrojasmone

of dione -7 yielding

dihydrocinerone

glycol,

the dioxane

Acetal -5 was refluxed

Dione _7 was shown to be the initial product

catalyzed

exclusively

arose reaction

of acetic from enone

The acid-

documented.

in 40% overall

yield.

in the enone -t diketone

systems,

J. E. McMurry

and T. L. Ho for helpful

Nakai and Eiji Wada for sending

spectra

of dihydro-

jasmone. References 1.

See, for example, (1966).

2.

T. L. Ho, Synth. Commun.,

3.

cf. C. Djerassi, G. Rosenkranz, 72, 4534 (1950).

4.

I. G. Tishchenko, V. N. Sytin and I. F. Revinskii, Zh. Org. Khim., 13, 1154 (1977); C. A. 87, 102095y (1977). Enone 1 was also conveniently prepared from propionaldehyde and dimethyl (2-oxooctyl)phosph&ate (NaH, THF, 20°, 2h) in 87% yield, bp 700/1 mmHg.

5.

Bromo enone 2, IR (film) 1680,1635 cm-l, NMR (CDC13) 6 1.8 (3H, d,J=6 Hz), 4.73 (lH,m), 6.17 (lH,d,J=16 Hz), 6.9 (lH,dd,J=16,8 Hz); y-methoxy enone 2, bp 80-33O/O.6 mmHq, IR (film) 1685,164O cm-', NMR (CDC13) 6 1.27 (3H,d,J=6.5 Hz), 3.3 (3H,s), 3.93 (lH,m), 6.2 (lH,d,J=16 Hz), 6.72 (lH,dd,J=16,6 Hz); diacetal 4, NMR (CDC13) 6 1.681(4H,s),3.82 (~H,s); dioxane ketone 2, bp 89-900/0.1 mmHg, IR(film) 1710, 1110 (strong) cm , NMR (CDC13) 6 1.08 (3H,d,J=6 Hs),3.67 (4H,s), 3.2-4.2 (2H,m), HRMS m/z talc. for C13H2403 : 228.1725; found 228.1700.

6.

G. W. Watt, P. S. Gentile

7.

P. B. Sollman

and R.

8.

F. B. LaForqe

and W. F. Barthel,

(Received

in

J, A. Marshall,

and Notes

USA

M.

fl, 265

M. T. Pike and R. D. Carroll,

(19741, ibid., 2,

and J. Pataki,

(1961).

J. Org. Chem., lo, 222 (1945).

1982)

J. Amer. Chem. Sot.,

J. Amer. Chem. Sot., z,

Dodson, J. Org. Chem., 26, 4180

20 September

2933

7 (1981).

J. Romo, St, Kaufmann

and E. P. Helvenston,

J. Org. Chem., 2,

2752

(1955).