Cinnamylidene camphor derivatives and their use as UV-A protecti

Details Cinnamylidene camphor derivatives and their use as UV-A protecti Cinnamylidene camphor derivatives and their use as UV-A protecti

1998-09-03

2000-07-11

Padmanabhan, Sreeni

Drug, bio-affecting and body treating compositions

Topical sun or radiation screening, or tanning preparations

514680, 514683, 514692, 514844, 568327, 568329, 568339, 568376, 564305, A61K 742, A01N 3504, C07C 4923

Patent

active

060868570

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to cinnamylidenecamphor derivatives of the formula (1) ##STR2## and to their use in cosmetic and pharmaceutical formulations.
Sun protection filters based on camphor derivatives are known. DE 23 36 219 describes sulfonated benzylidene- and cinnamylidene-camphor derivatives which are unsubstituted or substituted by methyl, methoxy or chlorine in position 4 of the phenyl ring.
DE 34 45 712 describes a number of unsaturated camphor derivatives, preferably benzylidenecamphor derivatives, which are suitable as pharmaceuticals for the treatment of cutaneous disorders.
DE 44 26 216 describes benzylidenenorcamphor derivatives which can be used as sun filters and to prevent inflammations and cutaneous disorders.
DE 44 24 489 describes a process for preparing substituted 4-methylidenecinnamic acid derivatives.
The requirements to be met by a sunscreen agent intended to be employed as UV-A filter are numerous (Sunscreens, ed. N. J. Lowe, N. A. Shaath, Marcel Dekker Inc., New York 1990, pages 230-231). The most important are: small, in order to preclude coloration of the sunscreen product or staining of the clothing after use; on the skin; cosmetic solvents and preparations;
The known cinnamylidenecamphor derivatives are wide-band UV filters which have an inadequate protective effect in the UV-A region. Furthermore, their solubility, particularly in the oil phase, is unsatisfactory for some applications.
It is an object of the present invention to provide a compound which is suitable as UV-A filter and which has, in particular, good stability to light, good solubility in the oil phase and a pronounced absorption maximum in the UV-A region.
We have found that this object is achieved by cinnamylidenecamphor derivatives of the formula (1) ##STR3## where the diene system is in the Z,Z, Z,E, E,Z or E,E configuration, and R.sup.1 is H, CH.sub.3, NR.sup.3 H, NR.sup.3.sub.2, optically active form, ie. as defined enantiomer or as any mixture of the enantiomers, or norcamphor (2b), in the presence of a base, with or without the addition of one or more solvents, with cinnamaldehyde (3), as can be obtained as disclosed in EP 392 579 or DE 3831713, at from 0.degree. C. to +200.degree. C. The cinnamaldehyde (3) can be employed as Z or E isomer of the double bond or as any mixture of the geometric isomers.
The cinnamaldehyde (3) can also be prepared by an enol ether insertion into benzaldehyde acetals. For this, the benzaldehyde acetal (4) is reacted with an enol ether (5) with Lewis acid catalysis to give (6) from which the cinnamaldehyde (3) is obtained by hydrolysis. ##STR4##
For this reaction, benzaldehyde acetal (4) is reacted with the enol ether (5) in equimolar amounts. The catalyst preferably employed is boron trifluoride etherate in an amount of 0.001-0.01 mol per mole of acetal (4). The reaction is carried out at from 0 to 60.degree. C., preferably from 20 to 40.degree. C.
The resulting insertion product (6) is converted by hydrolysis, preferably with aqueous hydrochloric acid, into the cinnamaldehyde (3).
The compound (1) according to the invention can in principle be in the form of its various geometric isomers, ie. with the diene system in the Z,Z, Z,E, E,Z or E,E configuration. The all-E isomer is particularly preferred as cosmetic sunscreen agent.
The reaction of (2) and (3) to give (1) is known in the literature under the collective term "aldol condensation" (Organic Reactions 1968, Vol 16) and can be carried out in a conventional way.
To prepare the compounds according to the invention, (2) and (3) ##STR5## are reacted in molar ratios of from 0.1:1 to 1:10. The molar ratios can be varied within wide limits: an excess of (3) over (2) is advantageous because the cinnamaldehyde is prone to side reactions, eg. because of its sensitivity to oxidation. It is particularly advantageous to use a 1.01-1.2-fold molar excess of (3) over (2), but the use of a considerably greater excess is not disadvantageous either.
The sequence in which (2) and (3) are introduced into the reaction is immaterial. T

REFERENCES:
patent: 3781417 (1973-12-01), Welters et al.
patent: 4766235 (1988-08-01), Lang et al.
patent: 5639883 (1997-06-01), Poetsch et al.
patent: 5730960 (1998-03-01), Stein et al.

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