- O-Silylated C3-halohydrins as a novel class of protected building blocks for total, regio- and stereocontrolled synthesis of glycerolipid frameworks
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We propose O-silylated C3-halohydrins [1(3)-O-silyl-2-O-acyl-, 1,2(2,3)-O-bis(silyl)-, and 1(3)-O-acyl-2-O-silyl-3(1)-halo-sn-glycerides] as new chirons in the total synthesis of glycerolipid constructs. These are efficiently producible via opening of the
- Stamatov, Stephan D.,Stawinski, Jacek
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experimental part
p. 463 - 477
(2010/02/16)
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- Regioselective and stereospecific acylation across oxirane- and silyloxy systems as a novel strategy to the synthesis of enantiomerically pure mono-, di- and triglycerides
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A trifluoroacetate-catalyzed opening of the oxirane ring of glycidyl derivatives bearing allylic acyl or alkyl functionalities with trifluoroacetic anhydride (TFAA), provides an efficient entry to configurationally homogeneous 1(3)-acyl- or 1(3)-O-alkyl-sn-glycerols. Selective introduction of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl- (TIPS) transient protections at the terminal sites within these key intermediates secures 1(3)-acyl- or 1(3)-O-alkyl-3(1)-O-TBDMS (or TIPS)-sn-glycerols as general bifunctional precursors to 1,2(2,3)-diacyl-, 1(3)-O-alkyl-2-acyl- and 1,3-diacyl-sn-glycerols and hence triester isosters. Incorporation of a requisite acyl residue at the central carbon of the silylated synthons with a subsequent Et3N·3HF-promoted, direct trichloroacetylation across the siloxy system by trichloroacetic anhydride (TCAA), followed by cleavage of the trichloroacetyl group, affords the respective 1,2(2,3)-diacyl- or 1(3)-O-alkyl-2-acyl-sn-glycerols. Alternatively, a reaction sequence involving: (i) attachment of a trichloroacetyl fragment at the stereogenic C2-centre of the monosilylated glycerides; (ii) replacement of the silyl moiety by a short- or long-chain carboxylic acid residue by means of the acylating agent: tetra-n-butylammonium bromide (TBABr)-carboxylic acid anhydride (CAA)-trimethylsilyl bromide (TMSBr); and (iii) removal of the trichloroacetyl replacement, provides pure 1,3-diacyl-sn-glycerols. The TBABr-CAA-TMSBr reagent system allows also a one-step conversion of 1,2-diacylglycerol silyl ethers into homochiral triglycerides with predefined asymmetry and degree of unsaturation. These compounds can also be accessed via a two-step one-pot approach where the trichloroacetyl derivatives of 1,2(2,3)- or 1,3-diacyl-sn-glycerols serve as triester building blocks for establishing the third ester bond at preselected C3(1)- or C2-positions within the glycerol skeleton at the very last synthetic stage. In all instances, the target compounds were produced under mild conditions, in high enantiomeric purity, and in practically quantitative yields. The Royal Society of Chemistry 2007.
- Stamatov, Stephan D.,Stawinski, Jacek
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p. 3787 - 3800
(2008/10/09)
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- A direct transformation of O-silyl groups into O-trichloroacetates. A novel synthetic approach to protein kinase C ligands: 1-Oleoyl-2-acetyl- and 1-hexadecyl-2-acetyl-sn-glycerols
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A fluoride ion-promoted direct esterification of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl (TIPS)-protected glycerol derivatives by means of trichloroacetic anhydride (TCAA), followed by removal of the trichloroacetyl transient protection, provides a new, efficient entry to stereochemically pure 1-oleoyl-2-acetyl- and 1-O-hexadecyl-2-acetyl-sn-glycerols.
- Stamatov, Stephan D.,Kullberg, Martin,Stawinski, Jacek
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p. 6855 - 6859
(2007/10/03)
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Cosmetic composition containing DOPA derivatives
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A composition for topical application to human hair or skin contains a chemical analogue of dihydroxyphenyl alanine (DOPA). This chemical analogue can be absorbed by skin or by a hair follicle and metabolised in-vivo, thus leading to the formation of melanin in skin or to the growth of melanin-pigmented hair. Consequently the composition can give controlled skin darkening to mimic sun-induced tanning or can bring about the growth of dar hair in place of the grey or white hair.
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin or hair for inducing, maintaining or increasing hair growth comprises a glycosaminoglycanase inhibitor chosen from aldonomonolactones, alduronomonolactones and acylated monosaccharides, and a cosmetically acceptable vehicle for the inhibitor; the total amount of the inhibitor present in the composition being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than 3 months, by at least 10% more than that obtainable using a control composition from which the said inhibitor has been omitted, in accordance with the Rat Hair Growth Test.
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- Cosmestic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamic acid derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Method of growing hair
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A method for inducing, maintaining or increasing hair growth which is achieved by topically applying a preserved composition to mammalian skin and hair in a mammal having need thereof, the composition comprising a hexosaccharic acid, salts and esters thereof, in an amount sufficient to induce, maintain or increase hair growth.
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- Hair growth composition containing citric acid esters
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Triesters of citric acid are used for inducing, maintaining or increasing hair growth. Compositions for topical application to mammalian hair or scalp comprise an effective amount of from 1% to 99% by weight of an ester of citric acid having the structure (1): where, R1, R2 and R3 each independently represent a branched or unbranched alkyl, alkenyl, aryl, alkylaryl or arylalkyl group, each said group having from 1 to 18 carbon atoms, R4 represents -H, or a branched or unbranched saturated or unsaturated acyl, alkyl, aryl, alkylaryl or aylalkyl group having from 1 to 18 carbon atoms, in the presence of a cosmetically acceptable vehicle for the citric acid ester and in the absence of solid absorbent for the ester;, said effective amount of said ester being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than three months, by at least 10% more than that obtainable using a control composition from which the said ester has been omitted, in accordance with the Rat Hair Growth Test.
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin or hair comprises: (a) a growth factor chosen from: (i) transforming growth factor alpha (TGF-α), (ii) transforming growth factor beta (TGF-β), (iii) insulin-like growth factor-1 (IGF-1), (iv) fragments thereof of one or more of said growth factors, and (v) mixtures thereof of said growth factors or fragments of said growth factors; and (b) a cosmetically acceptable vehicle for the growth factor or fragments thereof; the total amount of growth factor being sufficient to increase hair growth in the rate, when the composition is applies topically thereto over a period of no more than 3 months, by at least 10% more than that obtainable using a control composition from which the said growth factor has been omitted, in accordance with the Rat Hair Growth Test.
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- Lactams, their synthesis and use in cosmetic compositions
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A composition suitable for topical application to mammalian skin or hair for inducing, maintaining or increasing hair growth comprises: (i) a chemical inhibitor of glycosidase activity chosen from lactams having the structure: STR1 where A1 and A6 are --H, --CH3, STR2 --CH2 OT or STR3 A1 and A6 being the same or different, and at least one of which being the group: STR4 in a lactam ring; and where Q is --OT', --NHT' or a lactam linkage to A1 or A6 ; the Q groups being the same or different, and at least one of which is involved in a lactam linkage; and where T is the same or different and is chosen from --H, --Cp H2p+1 or a metal ion, T' is --H or --COCp H2p+1, and p is an integer of from 1 to 22; provided that: where any of the Q groups is --OT' or --NHT', then that group or groups can be of either stereochemical configuration with respect to the plane of the ring; and (ii) a cosmetically acceptable vehicle for the chemical inhibitor. Certain novel lactams are also claimed.
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- Carbohydrate lactam derivatives and their use in cosmetic compositions
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A composition suitable for topical application to mammalian skin or hair for inducing, maintaining or increasing hair growth comprises: (i) a chemical inhibitor of glycosidase activity chosen from lactams having the structure: where A1 and A6 are -H, -CH3,, - , or A1 and A6 being the same or different, and at least one of which being the group:, , , in a lactam ring;, and where Q is -OT?, -NHT? or a lactam linkage to A1 or A6;, the Q groups being the same or different, and at least one of which is involved in a lactam linkage;, and where T is the same or different and is chosen from, -H, -CpH2p+1or a metal ion,T? is -H or -COCpH2p+1, and, p is an integer of from 1 to 22;, provided that:, where any of the Q groups is, -OT? or -NHT?,then that group or groups can be of either stereochemical configuration with respect to the plane of the ring; and (ii) a cosmetically acceptable vehicle for the chemical inhibitor. Certain novel lactams are also claimed.
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