Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
  • C07D487/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains two hetero rings
  • C07D487/04—Ortho-condensed systems

Definitions

• Personal care absorbent products such as infant diapers, adult incontinent pads, and feminine care products, typically contain a fluid absorbent core.
• Many absorbent articles include the fluid absorbent core disposed between a top sheet and a back sheet.
• the top sheet can be formed from a fluid-permeable material adapted to promote fluid transfer into the absorbent core, such as upon a liquid insult, usually with minimal fluid retention by the top sheet.
• U.S. southern pine fluff pulp is commonly used in the absorbent core, generally in the form of a fibrous matrix, and sometimes in conjunction with a superabsorbent polymer (SAP) dispersed throughout the fibrous matrix.
• SAP superabsorbent polymer
• This fluff pulp is recognized worldwide as the preferred fiber for absorbent products, based on factors such as the fluff pulp’s high fiber length, fiber coarseness, and its relative ease of processing from a wet-laid and dried pulp sheet to an air-laid web.
• the raw material for this type of cellulosic fluff pulp is Southern Pine (e.g., Loblolly Pine, Pinus taeda L.,).
• the raw material is renewable, and the pulp is easily biodegradable.
• these fibers are inexpensive on a per mass basis but tend to be more expensive on per unit of liquid held basis.
• These fluff pulp fibers mostly absorb within the interstices between fibers. For this reason, a fibrous matrix readily releases acquired liquid on application of pressure. The tendency to release acquired liquid can result in significant skin wetness during use of an absorbent product that includes a core formed exclusively from cellulosic fibers. Such products also tend to leak the acquired liquid because liquid is not effectively retained in such a fibrous absorbent core.
• SAPs are water-swellable, generally water-insoluble absorbent materials having a high absorbent capacity for fluids. They are used in absorbent articles like baby diapers or adult incontinent products to absorb and hold body fluids. SAP, upon absorption of fluids, swells and becomes a gel holding more than its weight of such fluids.
• the SAPs in common use are mostly derived from acrylic acid. Acrylic acid-based polymers also comprise a meaningful portion of the cost structure of diapers and incontinent pads.
• SAPs are designed to have high gel strength (as demonstrated by high absorbency under load or AUL). The high gel strength (upon swelling) of currently used SAP particles helps them to retain significant void space between particles, which is helpful for rapid fluid uptake. However, this high“void volume” simultaneously results in significant interstitial (between particles) liquid in the product in the saturated state. When there is interstitial liquid the“rewet” value or“wet feeling” of an absorbent product is compromised.
• Some absorbent articles such as diapers or adult incontinence pads, also include an acquisition and distribution layer (ADL) for the collection, and uniform and timely distribution of fluid from a fluid insult to the absorbent core.
• ADL acquisition and distribution layer
• An ADL is usually placed between the top sheet and the absorbent core, and normally takes the form of composite fabric with most likely the top-one third of the fabric having low density (higher denier fiber) with relatively large voids and higher void volume for the effective acquisition of the presented fluid, even at relatively higher discharge rates.
• the middle one-third of the composite fabric of the ADL is usually made of higher density (low denier) fibers with smaller voids, while the lower one- third of the fabric is made of even higher density (lower and smaller denier) fibers and yet with finer voids.
• the higher density portions of the composite have more and finer capillaries and hence develop greater capillary pressure, thus moving greater volumes of fluid to the outer regions of the structure thus enabling the proper channelization and distribution of the fluid in an evenly fashion to allow the absorbent core to take up all of the liquid insult in a time bound manner to allow SAP within the absorbent core to hold and to gel the insult neither too slow nor too fast.
• the ADL provides for more rapid liquid acquisition (minimizing flooding in the target zone), and ensures more rapid transport and thorough distribution of the fluid into the absorbent core.
• the absorbent core is adapted to retain fluid, and as such may consist of one or more layers, such as layers to acquire, distribute, and/or store fluid.
• a matrix of cellulose fibers such as in the form of an air-laid pad and/or non-woven web, is used in (or as) the absorbent core of absorbent articles.
• the different layers may consist of one or more different types of cellulose fibers, such as cross-linked cellulose fibers.
• the absorbent core may also include one or more fluid retention agents, such as one or more SAPs, distributed throughout the fiber matrix, usually as particles.
• the back sheet is typically formed from a fluid-impermeable material to form a barrier to prevent retained fluid from escaping.
• the absorbent article when the absorbent article is wet from one or more liquid insults, the chances for the fluid coming in contact with the skin increases profoundly, and if left unchanged for a long time can result in diaper rash for infants or dermatitis problem in adults, thereby posing a skin wellness hazard.
• the only way to know whether the diaper or the incontinent pad is dry or wet is to physically inspect it. During day time this may not pose a significant problem because a caregiver can check the diapers or adult incontinent products as many times as desired.
• inspections during night time can be a discomfort to the baby as well as to the adult, disturbing their sleep.
• frequent night time inspections such as several times in a single night, can disrupt the wearer’s sleeping pattern, which poses health hazard to baby as well as the adult patient.
• an article of clothing such as pants, pajamas, and/or undergarments, is worn over the diaper or absorbent article. Accordingly, even absorbent articles that incorporate different types of wetness and/or moisture indicators pose difficulties in timely discovery of an insult.
• the mechanisms for such indicators generally fall into three broad categories: (1) imprinting a moisture indicating pattern on one of the piles of the absorbent article; (2) discrete moisture- indicating strips or layers that are incorporated between the layers of the absorbent article; and (3) a discrete (i.e., not part of the absorbent article’s construction) indicating strip that is fastened to the interior of the absorbent article immediately prior to use.
• these visual indicators are deficient in low-light (e.g., night time) situations. Appearing or disappearing inks must be directly visually detected, such that the caregiver can see the absorbent product. In low-light situations, this may require both a light source (e.g., overhead light or flashlight), as well as the removal of covering garments (e.g., pajamas or undergarments). Fluorescent indicators suffer similar issues, in that they require an external light source to excite the fluorescent compound. Such excitation is typically provided by exposing the indicator to UV light (which presents health concerns to the wearer and caregiver) and must be in direct optical communication with the fluorescent compound, which then requires removal of covering garments, blankets, etc. Therefore, the use of visual indicators previously used to detect wetness in absorbent garments suffers many disadvantages in low-light situations, which greatly reduces the usefulness of their indication mechanisms.
• the present disclosure features a method of making coelenterazine, including: coupling 4-(5-amino-6-benzylpyrazin-2-yl)phenol (coelenteramine) with 3-(4- (benzyloxy)phenyl)-2-oxopropanal to provide 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4- hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one; and deprotecting the 8-benzyl-2-(4- (benzyloxy)benzyl)-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one to provide 8- benzyl-2-(4-hydroxybenzyl)-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one
• the present disclosure features a method of making 3-(4- (benzyloxy)phenyl)-2-oxopropanal, including providing 1-(benzyloxy)-4- (chloromethyl)benzene, and reacting the 1-(benzyloxy)-4-(chloromethyl)benzene in two steps to provide 3-(4-(benzyloxy)phenyl)-2-oxopropanal.
• the present disclosure features a method of making coelenterazine, including:
• the present disclosure features a method of making coelenterazine, including:
• the present disclosure features a method of making coelenterazine, including:
• the present disclosure features a method of making coelenterazine, including:
• the present disclosure features a method of making coelenterazine, including:
• the present disclosure features a method of making coelenterazine, including:
• the present disclosure features a method of making coelenterazine, including (a) reacting pyrazin-2-amine (24) with benzyl chloride to provide 3- benzylpyrazin-2-amine (25) (e.g., under Grignard conditions, such as by first providing a solution of magnesium, iodine, and ethyl bromide in a solvent before reacting pyrazin-2-amine (24) with benzyl chloride to provide 3-benzylpyrazin-2-amine (25); (b) reacting 3- benzylpyrazin-2-amine (25) with N-bromosuccinimide to provide 3-benzyl-5-bromopyrazin- 2-amine (2); (c) reacting the 3-benzyl-5-bromopyrazin-2-amine (2) in two sequential steps to provide 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine); and (d) coupling the 4-(5-amino-6-benz
• the present disclosure features a method of making an absorbent article, including incorporating the coelenterazine made according to the methods of the present disclosure into an absorbent article.
• the present disclosure features an absorbent article, including the coelenterazine synthesized by the methods of the present disclosure.
• coelenterazine in high yield and with good purity.
• articles including the coelenterazine and coelenterazine derivatives are also disclosed.
• Representative absorbent articles include disposable diapers and adult incontinence products.
• Chemiluminescence results from a chemical reaction that produces light and therefore provides a lighted indication of moisture that can be seen in low light and/or in the absence of light, and through clothes. Furthermore, chemiluminescence requires no external excitation light, as is required for photoluminescent (e.g., fluorescence) indicators. Accordingly, by generating light upon contact with an aqueous system (e.g., urine), the disclosed embodiments greatly enhance the ability of absorbent articles to indicate the occurrence of an insult in darkened conditions (e.g., at night). Moreover, by generating light that can be seen through clothing, a caregiver may be able to ascertain the occurrence of an insult without having to move or disturb the infant or adult wearer of such an absorbent article, such as during sleep.
• an aqueous system e.g., urine
• the articles provided herein may provide the distinct advantages of insult indication at night and through clothes, which may reduce or even eliminate the need for caregivers to disturb the sleep (e.g., by pulling down clothes and/or shining a light) of one wearing an absorbent article in order to test for an insult. Further, because light (e.g., visible light) is produced by the chemiluminescent systems disclosed herein, there is no need to expose the absorbent article and/or the wearer to UV light in order to determine whether an insult has occurred, allowing health concerns associated with UV radiation to be avoided. Examples of articles including chemiluminescent materials are described, for example, in U.S. Application No. 14/516,255, the disclosure of which is herein incorporated in its entirety.
• the articles of the present disclosure provide improved ease with which an insult can be detected, which allows the caregiver to check for an insult more frequently, due to the reduced interruption required. More frequent checks may allow an insult to be detected sooner and the absorbent article changed soon after the insult, thereby reducing the amount of time the insult contacts the wearer’s skin, as well as reducing the possibility of fluid from multiple insults contacting the wearer’s skin.
• the skin health and general comfort of the wearer are improved when the length of time that fluid is in contact with the skin is reduced.
• the component amounts/ratios can be calibrated so that instead of seeing a peak and then a fade after each of a sequence of insults, once there is sufficient water present in the absorbent article, the luminescence can be maintained at a relatively steady intensity (e.g., the luminescence can vary less than about 30%, less than about 20%, less than about 10%, less than 30%, less than 20%, or less than 10%,) over a period of time (e.g., about 24 hours, about 12 hours, about 6 hours, about 3 hours, about 2 hours, about 1 hour, about 30 minutes, about 15 minutes, 24 hours, 12 hours, 6 hours, 3 hours, 2 hours, 1 hour, 30 minutes, or 15 minutes).
• a relatively steady intensity e.g., the luminescence can vary less than about 30%, less than about 20%, less than about 10%, less than 30%, less than 20%, or less than 10%,
• a period of time e.g., about 24 hours, about 12 hours, about 6 hours, about 3 hours, about 2 hours, about 1 hour, about
• the word“about” as it relates to a quantity indicates a number within range of minor variation above or below the stated reference number.
• “about” can refer to a number within a range of 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% above or below the indicated reference number.
• “about” refers to a number within a range of 5% above or below the indicated reference number.
• “about” refers to a number within a range of 10% above or below the indicated reference number.
• “about” refers to a number within a range of 1% above or below the indicated reference number.
• the present disclosure features a method of making coelenterazine, including coupling coelenteramine, or a salt thereof, with a protected 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one; or coupling coelenteramine, or a salt thereof, with 1,1-diethoxy- 3-(4-hydroxyphenyl)propan-2-one (14), to provide coelenterazine, or a salt thereof.
• the present disclosure features a method of making coelenterazine, including coupling coelenteramine, or a salt thereof, with a protected 1,1-dimethoxy-3-(4- hydroxyphenyl)propan-2-one (e.g., a silyl-protected 1,1-dimethoxy-3-(4- hydroxyphenyl)propan-2-one), to provide coelenterazine, or a salt thereof.
• a protected 1,1-dimethoxy-3-(4- hydroxyphenyl)propan-2-one e.g., a silyl-protected 1,1-dimethoxy-3-(4- hydroxyphenyl)propan-2-one
• the present disclosure features a method of making coelenterazine, including coupling 4-(5-amino-6-benzylpyrazin-2-yl)phenol (coelenteramine) with 3-(4- (benzyloxy)phenyl)-2-oxopropanal to provide 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4- hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one; and deprotecting the 8-benzyl-2-(4- (benzyloxy)benzyl)-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one to provide 8- benzyl-2-(4-hydroxybenzyl)-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one
• the coelenteramine can be made via different routes, as outlined below.
• the methods can provide coelenterazine in good yield and at good purity.
• the coelenteramine is made by first (a1) reacting 3- benzylpyrazin-2-amine (25) with N-bromosuccinimide to provide 3-benzyl-5-bromopyrazin- 2-amine (2), or a salt thereof; or by (a2) reacting 3,5-dibromopyrazin-2-amine and (bromomethyl)benzene in the presence of zinc, iodine, and a palladium catalyst to provide the 3-benzyl-5-bromopyrazin-2-amine (2), or a salt thereof.
• step (b) the 3-benzyl-5- bromopyrazin-2-amine (2) is then reacted in two sequential steps to provide 4-(5-amino-6- benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the reaction of (a1) 3-benzylpyrazin-2-amine (25) with N-bromosuccinimide can be carried out in an organic solvent, such as CHCl 3 (chloroform) at room temperature (e.g., about 22 °C to 23 °C, 22 °C to 23 °C, or 22 °C) at atmospheric pressure (i.e., about 1 atm, or 1 atm).
• an organic solvent such as CHCl 3 (chloroform) at room temperature (e.g., about 22 °C to 23 °C, 22 °C to 23 °C, or 22 °C) at atmospheric pressure (i.e., about 1 atm, or 1 atm).
• (a1) provides 3-benzyl-5-bromopyrazin-2-amine (2) in a yield of about 60% to about 85 % (e.g., 60% to 85 %) relative to 3-benzylpyrazin-2-amine (25) and in a purity of at least about 85 % (e.g., a purity of about 85% to about 95%, a purity of about 85% to about 100%, a purity of 85% to 95%, or a purity of 85% to 100%).
• % yield refers to mole % yield.
• the purity of a given compound when accompanied by the % yield of the given compound refers to the weight percent purity relative to the mass of the pure compound calculated based on mole % yield.
• the palladium catalyst is bis(triphenylphosphine) palladium(II) dichloride.
• the palladium catalyst can be present in an amount of about 5 to about 10 mole percent (e.g., 5 to 10 mole percent) relative to 3,5-dibromopyrazin-2-amine.
• (a2) includes about 1:2 to about 1:3 molar equivalent (e.g., 1:2 to 1:3 molar equivalent) of 3,5-dibromopyrazin-2-amine to (bromomethyl)benzene.
• (a2) can provide 3- benzyl-5-bromopyrazin-2-amine (2) in a yield of about 55% to about 75% (e.g., 55% to 75%) relative to the 3,5-dibromopyrazin-2-amine at a purity of about 80% to about 95% (80% to 95%).
• (a2) includes reacting 3,5-dibromopyrazin-2-amine and (bromomethyl)benzene for a duration of about 18 hours to about 30 hours (e.g., 18 hours to 30 hours).
• the reaction of 3,5-dibromopyrazin-2-amine and the (bromomethyl)benzene can occur at a temperature of about 25 to about 40 °C (e.g., 25 to 40 °C) at a pressure of about 1 atm (e.g., 1 atm).
• step (b) includes a first step of reacting the 3-benzyl-5- bromopyrazin-2-amine (2) with 4-methoxyphenyl boronic acid (4) in the presence of a palladium catalyst to provide 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof.
• the palladium catalyst can be a palladium (0) catalyst, for example, tetrakis(triphenylphosphine)palladium(0).
• the palladium catalyst can be present in an amount of about 5 to about 10 percent by weight (e.g., 5 to 10 percent by weight) relative to the 3- benzyl-5-bromopyrazin-2-amine (2).
• the first step in (b) can include about 1:1 to about 1:1.3 molar equivalent of the 3-benzyl-5-bromopyrazin-2-amine (2) to 4-methoxyphenyl boronic acid (4).
• the 3-benzyl-5-bromopyrazin-2-amine (2) and the 4- methoxyphenyl boronic acid (4) are reacted together for a duration of about 120 minutes to about 300 minutes (e.g., 120 minutes to 300 minutes).
• the 3-benzyl-5-bromopyrazin-2-amine (2) and the 4-methoxyphenyl boronic acid (4) can be reacted together at a temperature of about 60 °C to about 90 °C (e.g., 60 °C to 90 °C) and at atmospheric pressure (i.e., a pressure of about 1 atm, or 1 atm).
• the first step in (b) can provide the 3-benzyl-5-(4-methoxyphenyl)pyrazin- 2-amine (5), or salt thereof, in a yield of about 60% to about 85% (e.g., 60% to 85%) relative to the 3-benzyl-5-bromopyrazin-2-amine (2) of the product at a purity of about 80 to about 95% (i.e., a yield of 60% to 85% of the 80%-95% pure product).
• yield at a given purity range refers to the yield of the product having the described purity range.
• (b) includes a first step of reacting the 3-benzyl- 5-bromopyrazin-2-amine (2) with (4-methoxyphenyl)boronic acid in the presence of a palladium catalyst (e.g., a palladium (II) catalyst, such as bis(benzonitrile) palladium(II) dichloride) to provide 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) or a salt thereof.
• a palladium catalyst e.g., a palladium (II) catalyst, such as bis(benzonitrile) palladium(II) dichloride
• the palladium (II) catalyst can be present in an amount of about 5 to about 10 (e.g., 5 to 10) mole percent relative to the 3-benzyl-5-bromopyrazin-2-amine (2).
• the reaction mixture can further include l,4-bis(diphenylphosphino)butane, for example, in an amount of about 5 to about 10 (e.g., 5 to 10) mole percent relative to the 3 -benzyl-5 -bromopyrazin-2-amine (2).
• the reaction mixture further includes toluene, aqueous sodium carbonate, and ethanol.
• the 3-benzyl-5-bromopyrazin-2-amine (2) can be reacted with the (4- methoxyphenyl)boronic acid for a duration of about 200 minutes to about 350 minutes (e.g., 200 to 350 minutes), and/or at a temperature of about 80 to about 110 °C (e.g., 80 to 100 °C) and at a pressure of about 1 atm (e.g., 1 atm).
• 3- benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) can be provided in a yield of about 65% to about 85% (e.g., 65% to 85%) relative to the 3-benzyl-5-bromopyrazin-2-amine (2).
• the 3- benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) can be isolated by diluting the reaction mixture with water and extracting with ethyl acetate. The ethyl acetate extract can be removed from the extract under reduced pressure to provide 3-benzyl-5-(4-methoxyphenyl)pyrazin-2- amine (5).
• the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof, regardless of whether obtained with a palladium (0) or palladium (II) catalyst, can be isolated by precipitation of the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) as a hydrochloride salt. Precipitation is advantageous as it can eliminate column chromatography, which can be laborious, costly, and time-consuming; and/or can also increase yield relative to column chromatography.
• isolating the 3 -benzyl-5 -(4-methoxypheny l)pyrazin- 2-amine (5) does not include chromatography (e.g., liquid chromatography), does not include recrystallization, or does not include chromatography and recrystallization.
• the reaction mixture from the reaction of 3-benzyl-5-bromopyrazin-2-amine (2) with (4-methoxyphenyl)boronic acid is diluted with aqueous sodium chloride solution (e.g., an about 20% (e.g., 20%) by weight sodium chloride solution) and extracted with ethyl acetate.
• the ethyl acetate extract can then be treated with HCl aqueous solution (e.g., an about 3N (e.g., 3N) HCl (aq) solution) and the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine hydrochloride salt product (5) can be isolated by filtration with a purity of about 75% to about 95% (e.g., 75% to 95%).
• HCl aqueous solution e.g., an about 3N (e.g., 3N) HCl (aq) solution
• 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine hydrochloride salt product (5) can be isolated by filtration with a purity of about 75% to about 95% (e.g., 75% to 95%).
• (b) further includes a second step of deprotecting the 3-benzyl- 5-(4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof, to provide the 4-(5-amino-6- benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the deprotection can include subjecting the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) to pyridinium chloride. Treatment with pyridinium chloride can proceed at an elevated temperature of about 180 to about 220 °C (e.g., 180 to 220 °C, or 200 °C) at atmospheric pressure.
• the elevated temperature can cause the pyridinium chloride to separate from the reaction mixture by evaporation from the reaction mixture.
• deprotection can include subjecting the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) to sodium hydride and ethanethiol in N,N’-dimethyl-formamide (DMF).
• the reaction mixture can be at a temperature of about 90 °C to about 120 °C (e.g., about 100 °C to 110 °C, 90 °C to 120 °C, or 100 °C to 110 °C) and/or for a period of about 15 minutes to about 5 hours (e.g., about 30 minutes to about 2 hours, about 30 minutes to about 1 hour, 30 minutes to 2 hours, 30 minutes to 1 hour, or 30 minutes).
• the mixture can be cooled to about 30 °C to about 50 °C (e.g., about 35 °C to about 45 °C, about 40 °C, 35 °C to 45 °C, or 40 °C), extracted with water and an organic solvent (e.g., ethyl acetate).
• the organic layer can then be separated, refluxed, and then cooled to about 5 °C to 20 °C (e.g., about 10 °C to 15 °C, 5 °C to 20 °C, or 10 °C to 15 °C), the 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine) can be isolated by filtration.
• the coelenteramine can be optionally purified by washing with an aqueous sodium hydroxide/dioxane solution, stirring with activated charcoal/silica, filtration, followed by precipitation by acidification of the filtrate, and isolation of the precipitated product by filtration.
• the deprotection can provide 4-(5-amino-6-benzylpyrazin- 2-yl)phenol (7) (coelenteramine) in a yield of about 90% to about 100% (e.g., 90% to 100%, at least about 95%, at least 95%, at least about 98%, at least 98%, at least about 99%, or at least 99%) at a purity of about 85% to about 100% (e.g., 85 % to 100 %, about 90%, or 90%) relative to 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5).
• coelenteramine is synthesized by (a) reacting 3,5- dibromopyrazin-2-amine and (bromomethyl)benzene in the presence of zinc, iodine, and a first palladium catalyst to provide 3 -benzyl-5 -bromopyrazin-2-amine (2); (b) reacting 3-benzyl-5- bromopyrazin-2-amine (2) with 4-methoxyphenyl boronic acid (4) in the presence of a palladium catalyst in a first step to provide a hydrochloride salt of 3-benzyl-5-(4- methoxyphenyl)pyrazin-2-amine (5), and deprotecting the hydrochloride salt of 3-benzyl-5-(4- methoxyphenyl)pyrazin-2-amine (5) in a second step to provide 4-(5-amino-6-benzylpyrazin- 2-yl)phenol (7) (coelenteramine).
• coelenteramine is synthesized by reacting pyrazin-2-amine with benzyl chloride to provide 3-benzylpyrazin-2-amine; reacting 3-benzylpyrazin-2-amine (25) with N-bromosuccinimide to provide 3-benzyl-5-bromopyrazin-2-amine (2); and reacting the 3-benzyl-5-bromopyrazin-2-amine (2) in two sequential steps to provide 4-(5-amino-6- benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the two sequential steps for providing coelenteramine from 3-benzyl-5-bromopyrazin-2-amine (2) can include a first step of reacting the 3-benzyl-5-bromopyrazin-2-amine (2) with silyl-protected 4-bromophenol in the presence of magnesium and a palladium catalyst to provide silyl-protected 4-(5-amino-6-benzylpyrazin- 2-yl)phenol.
• the palladium catalyst is tetrakis(triphenylphosphine)palladium(0), which can be present in an amount of 1 percent or more (e.g., 2 percent or more, 3 percent or more, 4 percent or more, 5 percent or more, 6 percent or more, 7 percent or more, 8 percent or more, or 9 percent or more) and/or 10 percent or less (e.g., 9 percent or less, 8 percent or less, 7 percent or less, 6 percent or less, 5 percent or less, 4 percent or less, 3 percent or less, or 2 percent or less) by weight relative to the 3-benzyl-5- bromopyrazin-2-amine (2).
• 1 percent or more e.g., 2 percent or more, 3 percent or more, 4 percent or more, 5 percent or more, 6 percent or more, 7 percent or more, 8 percent or more, or 9 percent or more
• 10 percent or less e.g., 9 percent or less, 8 percent or less, 7 percent or less, 6 percent or less, 5 percent or less, 4 percent or
• the two sequential steps can include a second step of deprotecting the silyl-protected 4-(5-amino-6-benzylpyrazin-2-yl)phenol to provide the 4-(5- amino-6-benzylpyrazin-2-yl)phenol (7), for example by subjecting the silyl-protected 4-(5- amino-6-benzylpyrazin-2-yl)phenol to aqueous HC1.
• This synthesis procedure reduces or eliminates the use of: n-butyl lithium-in the first step of the synthesis, by replacing the n-butyl lithium reaction in toluene with benzyl chloride and THF (tetrahydrofuran).
• this synthesis presents the ability to scale up the reaction chemistry and can reduce the cost of the synthesis.
• the changes can improve the overall safety of the chemistry by replacing highly reactive materials with more stable materials.
• the omission of boronic acid compounds in the synthesis can greatly reduce the amount of expensive palladium catalyst in the reaction.
• coelenteramine is synthesized by reacting pyrazin-2-amine (24) with benzyl chloride to provide 3-benzylpyrazin-2-amine (25) (e.g., under Grignard conditions, such as by first providing a solution of magnesium, iodine, and ethyl bromide in a solvent before reacting pyrazin-2-amine (24) with benzyl chloride to provide 3-benzylpyrazin-2-amine (25); reacting 3-benzylpyrazin-2-amine (25) with N-bromosuccinimide to provide 3-benzyl- 5-bromopyrazin-2-amine (2); reacting 3-benzyl-5-bromopyrazin-2-amine (2) with 4- methoxyphenyl boronic acid (4) in the presence of a palladium catalyst in a first step to provide a hydrochloride salt of 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5), and deprotecting the hydrochlor
• the deprotection of 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) includes exposing the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) to an acidic environment, such as HBr in acetic acid, to provide 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the reaction of 3-benzylpyrazin-2-amine (25) with N-bromosuccinimide can be carried out in an organic solvent, such as CHCl 3 (chloroform) at room temperature (e.g., about 22 °C to 23 °C, 22 °C to 23 °C, or 22 °C) at atmospheric pressure (i.e., about 1 atm, or 1 atm).
• an organic solvent such as CHCl 3 (chloroform) at room temperature (e.g., about 22 °C to 23 °C, 22 °C to 23 °C, or 22 °C) at atmospheric pressure (i.e., about 1 atm, or 1 atm).
• 3-benzyl-5-bromopyrazin-2- amine (2) is provided in a yield of about 60% to about 85 % (e.g., 70-75 %) relative to 3- benzylpyrazin-2-amine (25) and in a purity of at least about 85 % (e.g., a purity of about 85% to about 95%, a purity of about 85% to about 100%, a purity of 85% to 95%, a purity of 90- 95%, or a purity of 85% to 100%).
• the 3-benzyl-5-bromopyrazin-2-amine (2) is reacted with 4- methoxyphenyl boronic acid (4) in the presence of a palladium catalyst to provide 3-benzyl-5- (4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof.
• the palladium catalyst can be a palladium (0) catalyst, for example, tetrakis(triphenylphosphine)palladium(0), or a palladium (II) catalyst, such as bis(benzonitrile) palladium(II) dichloride.
• the reaction mixture can further include 1,4-bis(diphenylphosphino)butane, for example, in an amount of about 5 to about 10 (e.g., 5 to 10) mole percent relative to the 3- benzyl-5-bromopyrazin-2-amine (2).
• the palladium catalyst can be present in an amount of about 5 to about 10 percent by weight (e.g., 5 to 10 percent by weight) relative to the 3-benzyl- 5-bromopyrazin-2-amine (2).
• the first step in (b) can include about 1:1 to about 1:1.3 molar equivalent of the 3-benzyl-5-bromopyrazin-2-amine (2) to 4-methoxyphenyl boronic acid (4).
• the 3-benzyl-5-bromopyrazin-2-amine (2) and the 4-methoxyphenyl boronic acid (4) are reacted together for a duration of about 120 minutes to about 300 minutes (e.g., 120 minutes to 300 minutes).
• the reaction solvent can include 1,4-dioxane and/or water.
• the reaction mixture further includes potassium carbonate in an amount of about 75 to about 85 mole percent relative to the 3-benzyl-5-bromopyrazin-2-amine (2).
• the 3-benzyl-5-bromopyrazin-2-amine (2) and the 4-methoxyphenyl boronic acid (4) can be reacted together for a duration of about 12 to about 36 hours (e.g., about 20 to 24 hours, about 12 to about 24 hours, or about 15 to 24 hours), and/or at a temperature of about 80 to about 110 °C (e.g., 80 to 100 °C, or 80 to 85 °C), and/or at atmospheric pressure (i.e., a pressure of about 1 atm, or 1 atm).
• the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof, can be provided in a yield of about 65% to about 95% (e.g., 85% to 90%, 80% to 95%, or 85% to 90%) relative to the 3-benzyl-5-bromopyrazin-2-amine (2), at a purity of for example, 90% to 95% (e.g., 92% to 95%).
• the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) can be isolated by diluting the reaction mixture with water and extracting with ethyl acetate. The ethyl acetate extract can be removed from the extract under reduced pressure to provide 3-benzyl-5- (4-methoxyphenyl)pyrazin-2-amine (5).
• the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof, regardless of whether obtained with a palladium (0) or palladium (II) catalyst, can be isolated by precipitation of the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5) as a hydrochloride salt. Precipitation is advantageous as it can eliminate column chromatography, which can be laborious, costly, and time-consuming; and/or can also increase yield relative to column chromatography.
• isolating the 3-benzyl-5-(4-methoxyphenyl)pyrazin- 2-amine (5) does not include chromatography (e.g., liquid chromatography), does not include recrystallization, or does not include chromatography and recrystallization.
• the reaction mixture from the reaction of 3-benzyl-5-bromopyrazin-2-amine (2) with (4-methoxyphenyl)boronic acid is diluted with aqueous sodium chloride solution (e.g., an about 20% (e.g., 20%) by weight sodium chloride solution) and extracted with ethyl acetate.
• the ethyl acetate extract can then be treated with HCl aqueous solution (e.g., an about 3N (e.g., 3N) HCl (aq) solution) and the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine hydrochloride salt product (5) can be isolated by filtration with a purity of about 75% to about 95% (e.g., 75% to 95%).
• HCl aqueous solution e.g., an about 3N (e.g., 3N) HCl (aq) solution
• 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine hydrochloride salt product (5) can be isolated by filtration with a purity of about 75% to about 95% (e.g., 75% to 95%).
• the 3-benzyl-5-(4-methoxyphenyl)pyrazin-2-amine (5), or salt thereof can then be deprotected to provide 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the deprotection includes exposing the 3-benzyl-5-(4-methoxyphenyl)pyrazin- 2-amine (5), or salt thereof, to an acid (e.g., HBr and acetic acid).
• the HBr can have an HBr concentration of 48% in water, and the aqueous HBr can be mixed with acetic acid in a ratio of from about 1:2 (e.g., from about 1:1.5, from about 1:1.25) to about 1:1 (e.g., to about 1:1.25, or to about 1:1.5).
• the deprotection can occur at a temperature of from about 100 °C (e.g., from about 105 °C, from about 110 °C, from about 115 °C) to about 120 °C (e.g., to about 115 °C, to about 110 °C, to about 105 °C) for a duration of from about 5 hours (e.g., from about 8 hours, from about 10 hours, from about 12 hours, or from about 14 hours) to about 18 hours (e.g., to about 14 hours, to about 12 hours, to about 10 hours, or to 8 hours), for example, from 8 to 10 hours, at atmospheric pressure.
• reaction mixture can be cooled, extracted with an organic solvent (such as ethyl acetate), and the organic solvent can be removed under reduced pressure.
• organic solvent such as ethyl acetate
• the residue can then be refluxed with a hydrocarbon (such as cyclohexane), filtered, isolated, and dried to provide 4-(5-amino- 6-benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• organic solvent such as ethyl acetate
• hydrocarbon such as cyclohexane
• the 4-(5-amino-6-benzylpyrazin-2- yl)phenol (7) (coelenteramine) can be obtained in an yield of from about 70% (e.g., from about 75%, from about 80%, or from 85%) to about 90 % (e.g., to about 85%, to about 80%, or to about 75%), for example, from 75% to 80%, at a purity of from about 85% (e.g., from about 87%, from about 90%, or from about 92%) to about 95% (e.g., to about 92 %, (e.g., to about 90%, or to about 87%), for example, a purity of about 90%, relative to 3-benzyl-5-(4- methoxyphenyl)pyrazin-2-amine (5).
• the silyl protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2- one is 3-(4-((tert-butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23).
• the 3-(4- ((tert-butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23) can be synthesized by: i) reacting 4-hydroxybenzaldehyde (8) with tert-butyldimethylsilyl chloride to provide 4-((tert- butyldimethylsilyl)oxy)benzaldehyde (20a); ii) reacting the 4-((tert- butyldimethylsilyl)oxy)benzaldehyde with sodium borohydride to provide (4-((tert- butyldimethylsilyl)oxy)phenyl)methanol (20b); iii) reacting the (4-((tert- butyldimethylsilyl)oxy)phenyl)methanol with methanesulfonyl chloride in the presence of a base (e.g., triethylamine) to provide tert-butyl(4-(chlor
• the tert-butyldimethylsilyl protected 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one can degrade in acidic conditions, and can be stabilized in a basic environment.
• a base can be added to the reaction mixture and/or during purification.
• the tert-butyl(4-(chloromethyl)phenoxy)dimethylsilane (21) can be purified by chromatography with an eluant that includes triethylamine.
• the 3-(4- ((tert-butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23) is further purified by chromatography with an eluant comprising triethylamine.
• the 3-(4-((tert-butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23) can be provided in a yield of about 20% to about 40% (e.g., 20% to 40%, about 20% to 25%, or 20% to 25%) relative to tert-butyl(4-(chloromethyl)phenoxy)dimethylsilane (21), at a purity of about 85% to about 95% (e.g., 85% to 95%, about 90%, or 90%).
• 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one (14) can be made, for example, according to the reaction scheme below.
• 4-(tert-butyldimethylsiloxy) benzyl chloride can be as synthesized above, and can be reacted in a Grignard reaction with methyl 2,2-dimethoxyacetate to provide 3-(4-((tert-butyldimethylsilyl)oxy)phenyl)-1,1-dimethoxypropan-2-one).
• the 4-(tert-butyldimethylsiloxy) benzyl chloride can be reacted with methyl 2,2- dimethoxyacetate in a Grignard reaction with Mg, and I 2 and dibromoethane as Grignard initiators to provide 3-(4-((tert-butyldimethylsilyl)oxy)phenyl)-1,1-dimethoxypropan-2-one).
• the present disclosure features a method of making 3-(4- (benzyloxy)phenyl)-2-oxopropanal, including providing 1-(benzyloxy)-4- (chloromethyl)benzene, and reacting the 1-(benzyloxy)-4-(chloromethyl)benzene in two steps to provide 3-(4-(benzyloxy)phenyl)-2-oxopropanal.
• the method of making 3-(4- (benzyloxy)phenyl)-2-oxopropanal does not include more than one palladium-catalyzed reaction, from an initial starting material of 4-hydroxybenzaldehyde.
• the method can include a first step of reacting the 1-(benzyloxy)-4- (chloromethyl)benzene with methyl 2,2-dimethoxyacetate under Grignard conditions (e.g., ethyl bromide, magnesium, and a catalytic amount of iodine) to provide 3-(4- (benzyloxy)phenyl)-1,1-dimethoxypropan-2-one.
• Grignard conditions e.g., ethyl bromide, magnesium, and a catalytic amount of iodine
• the 3-(4-(benzyloxy)phenyl)-1,1- dimethoxypropan-2-one can be purified by silica column chromatography.
• the method can include a second step of reacting the 3-(4-(benzyloxy)phenyl)-1,1- dimethoxypropan-2-one with acid (e.g., aqueous acid, such as 10% aqueous HCl)) to provide the 3-(4-(benzyloxy)phenyl)-2-oxopropanal.
• acid e.g., aqueous acid, such as 10% aqueous HCl
• the 3-(4-(benzyloxy)phenyl)-2-oxopropanal can be isolated in a yield of 60 to 75% (e.g., 65% to 70%) at a purity of 85 to 95% (e.g., 90%) relative to 1-(benzyloxy)-4-(chloromethyl)benzene.
• the intermediate 1-(benzyloxy)-4-(chloromethyl)benzene can be made, for example, by the following procedure.
• a mixture of 4-hydroxybenzaldehyde (8), benzyl chloride, and anhydrous potassium carbonate in N,N-dimethyl formamide can be formed, heated to a temperature of about 40-80 °C for a duration of from, for example, 5 hours to 3 days, under atmospheric pressure.
• the mixture can be cooled to room temperature, charged with water, and centrifuged or filtered to isolate the resulting 4- (benzyloxy)benzaldehyde.
• the 4-(benzyloxy)benzaldehyde can then be reduced with sodium borohydride to provide (4-(benzyloxy)phenyl)methanol.
• the sodium borohydride can be added at a temperature of about 45 to 50 °C dropwise to a solution of 4-(benzyloxy)benzaldehyde in methanol.
• the reaction mixture can then be cooled (e.g., to about 15 °C), acidified (e.g., with acetic acid), stirred with water, and the product can be isolated by filtration.
• the resultant product can be heated with an organic solvent (e.g., n-hexane), filtered, and dried to provide (4-(benzyloxy)phenyl)methanol.
• an organic solvent e.g., n-hexane
• the (4-(benzyloxy)phenyl)methanol can then be reacted with thionyl chloride to provide 1-(benzyloxy)-4-(chloromethyl)benzene (11).
• thionyl chloride can be formed, to which thionyl chloride can be added slowly at a temperature of from about 30 to about 35 °C.
• the solvent can be removed, and the residue can be extracted with water and an organic solvent, such as ethyl acetate.
• the pH of the layer can be adjusted to about 8 to 9 with an aqueous base, such as a soda ash aqueous solution, then the organic layer can be separated again, washed with a sodium chloride aqueous solution, and the organic layer is then separated and concentrated under reduced pressure. The residue can then be washed with an organic solvent, such as n-hexane, and the product can be isolated by filtration and dried to obtain the intermediate 1-(benzyloxy)-4-(chloromethyl)benzene.
• an aqueous base such as a soda ash aqueous solution
• the coelenterazine is obtained by coupling the 4-(5-amino-6- benzylpyrazin-2-yl)phenol (7) with silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan- 2-one or silyl-protected 1,1-dimethoxy-3-(4-hydroxyphenyl)propan-2-one to provide coelenterazine, or a salt thereof.
• the coelenterazine is obtained by coupling 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) with 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one (14) to provide coelenterazine, or a salt thereof.
• the coupling step can be conducted in the presence of dioxane, water, and HCl (e.g., at a ratio of about 90:5:5 dioxane to water to HCl; or at an HCl at 35%-38% concentration (i.e., concentrated HCl) to water ratio about 10: about 1 (e.g., 10:1) to about 1:about 1 (e.g., 1:1), where the dioxane:(HCl+H 2 O) ratio is about 9:1); and/or can be conducted at a temperature of about 60 to about 90 °C (e.g., 60 to 90 °C) and at a pressure of about
• the coupling reaction can be conducted in a solvent mixture of dioxane, methanol, and isopropyl alcohol.
• the methanol and the isopropyl alcohol can each independently be in the solvent mixture at a concentration of 3% or more (e.g., 5% or more, 7% or more, or 9% or more and/or 10% or less (e.g., 9% or less, 7% or less, or 5% or less) by volume.
• the methanol and the isopropyl alcohol are each independently in the solvent mixture at a concentration of about 5% (e.g., 5%) by volume.
• the 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) is reacted in the solvent mixture of dioxane, methanol, and isopropyl alcohol with silyl-protected 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one, such as 3-(4-((tert-butyldimethylsilyl)oxy)phenyl)-1,1- diethoxypropan-2-one (23).
• methanol can favor the reaction kinetics and yield by increasing the solubility of the 4-(5- amino-6-benzylpyrazin-2-yl)phenol (7) in the solvent mixture, thereby increasing its availability for reaction with silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one, silyl-protected 1,1-dimethoxy-3-(4-hydroxyphenyl)propan-2-one, or with 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one (14).
• the coupling reaction can be conducted at a temperature of about 60 to about 90 °C (e.g., about 70 °C to 85 °C, about 80 °C, or 80 °C) and at a pressure of about 1 atm (e.g., 1 atm); and/or can proceed for a duration of about 24 hours to about 36 hours (e.g., 24 to 36 hours, or 36 hours).
• the 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) is coupled with silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one (e.g., 3-(4-((tert- butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23)), silyl-protected 1,1- dimethoxy-3-(4-hydroxyphenyl)propan-2-one, or with 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one (14) at a molar ratio of about 1:1.3 to about 1:2.
• silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one e.g., 3-(4-((tert- butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23)
• the 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) is coupled with silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one (e.g., 3-(4-((tert- butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23)) at a molar ratio of about 1:1.3 to about 1.2 (e.g., about 1:1.3, or 1:1.3).
• silyl-protected 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one e.g., 3-(4-((tert- butyldimethylsilyl)oxy)phenyl)-1,1-diethoxypropan-2-one (23)
• the coupling reaction is monitored by reverse phase HPLC and stopped when 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) stops depleting, or when coelenterazine starts to decompose.
• reverse phase HPLC monitoring can be important, as the coelenterazine can start to decompose or degrade after the coelenteramine stops depleting.
• stopping the reaction mixture includes cooling the reaction mixture (e.g., to room temperature, about 23 °C, or 23 °C), and optionally stirring the reaction mixture with activated carbon and silica.
• the coelenterazine or a salt thereof can then be isolated by filtering the reaction mixture (if activated carbon and silica are used), by removal of solvents (e.g., under reduced pressure), trituration with ethyl acetate, followed by filtration to obtain the solid coelenterazine.
• the coelenterazine is isolated as a salt, such as a hydrochloride salt.
• the coelenterazine or a salt thereof is obtained in a yield of about 50% to about 70 % (e.g., 50% to 70%) relative to the 4-(5-amino-6- benzylpyrazin-2-yl)phenol (7), at a purity of about 55% to about 70% (e.g. 55% to 70%).
• coelenterazine or a salt thereof is obtained in a yield of about 60% to about 70 % (e.g., 60% to 70 %) relative to the 4-(5-amino- 6-benzylpyrazin-2-yl)phenol (7), at a purity of about 60% to about 75% (e.g., 60% to 75%).
• the coelenterazine (or salt thereol) is obtained at a purity of 60% to 65% in the isolated composition.
• the isolated coelenterazine, or salt thereof is stabilized (e.g., protected from degradation) by the presence of an amount of 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the isolated composition can include coelenterazine (or salt thereol) at an amount of 60% to 65% by weight and 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine).
• the isolated composition consists essentially of coelenterazine (or salt thereol) at an amount of 60% to 65% by weight and 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine); such that impurities present in the composition do not substantially contribute (e.g., contribute more than 10%, more than 5%, or more than 1%) to the luminescence of the coelenterazine, or salt thereof.
• the relative amount of coelenterazine (or salt thereof) to 4-(5-amino-6-benzylpyrazin- 2-yl)phenol (7) (coelenteramine) in the isolated composition can be assessed by liquid chromatography-mass spectrometry (LC-MS).
• LC-MS liquid chromatography-mass spectrometry
• a 1 mg/ml methanolic solution of the isolated coelenterazine composition can be diluted ten times into an injection solvent consisting of 70:30 reagent water : acetonitrile (v/v), each supplemented with 0.05% formic acid.
• the diluted solution including the isolated coelenterazine composition is separated by LC on a C-18 reverse phase column using a gradient elution.
• the separation provides a response for coelenterazine (or salt thereof) at about 1.7 min and a response for coelenteramine (7) at about 2.5 min.
• Tandem MS is configured to monitor the (M+H)+ parent ion of each compound which is subsequently fragmented into its characteristic daughter ion. The daughter ion intensity creates the chromatographic signal for each compound which is then integrated to produce an area for the signal.
• the parent ion for coelenterazine is 424.1 Da with a daughter ion at 302.2 Da.
• the parent ion for coelenteramine is 278.1 Da and its daughter is 132.0 Da.
• the ratio of the coelenterazine (or salt thereof) to coelenteramine in the isolated composition is about 20:1 or more (e.g., about 24:1 or more, about 30:1 or more, about 40:1 or more, about 50:1 or more, about 60:1 or more, about 70:1 or more, about 80:1 or more, or about 90:1 or more) and/or about 100:1 or less (e.g., about 90:1 or less, about 80:1 or less, about 70:1 or less, about 60:1 or less, about 50:1 or less, about 40:1 or less, about 30:1 or less, or about 24:1 or less).
• the ratio of the coelenterazine (or salt thereof) to coelenteramine in the isolated composition is 24:1 or more and/or 80:1 or less.
• the isolated composition can be incorporated into an article, such as an absorbent article, as will be described below.
• the coelenterazine is obtained by coupling 4-(5-amino-6- benzylpyrazin-2-yl)phenol (coelenteramine) with 3-(4-(benzyloxy)phenyl)-2-oxopropanal to provide 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin- 3(7H)-one; and deprotecting the 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4- hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one to provide 8-benzyl-2-(4-hydroxybenzyl)-6- (4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one (coelenterazine).
• Coupling the 4-(5-amino-6-benzylpyrazin-2-yl)phenol (coelenteramine) with the 3-(4- (benzyloxy)phenyl)-2-oxopropanal can occur in a solvent mixture that includes dioxane, water, and HCl (e.g., concentrated HCl, 36% HCl).
• the coupling reaction can be conducted at a temperature of 75 °C to 90 °C (e.g., 80 °C to 85 °C) for 12 to 36 hours (e.g., 24 hours) in an inert atmosphere.
• deprotecting the 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4- hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one includes a first deprotection step of exposing the 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin- 3(7H)-one to acid, such as HCl (e.g., concentrated HCl, 36% HCl).
• the reaction mixture can include an organic solvent, such as dioxane.
• the acid can be present in an amount equal to or in excess of the volume of the solvent mixture in the preceding coupling step.
• An intermediate deprotected product can be obtained, for example, by filtering the reaction mixture, collecting the solid residue, and drying the solid residue before proceeding to the following step.
• the first deprotection step can be conducted at a temperature of 25 °C to 40 °C (e.g., 30 to 35 °C), for a duration of from 30 minutes (e.g., from 1 hour) to 2 hours (e.g., to 1.5 hours).
• the intermediate deprotected product i.e., the solid residue
• an organic solvent e.g., toluene
• Deprotecting the 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4-hydroxyphenyl)imidazo[1,2- a]pyrazin-3(7H)-one can include a second deprotection step of exposing the dried intermediate deprotected product to acid, such as HCl (e.g., concentrated HCl, 36% HCl).
• acid such as HCl (e.g., concentrated HCl, 36% HCl).
• the reaction mixture can include an organic solvent, such as dioxane.
• the second deprotection step can include heating the intermediate deprotected product in HCl and the organic solvent to a first temperature of about 50 °C to 75 °C (e.g., from 60 °C to 70 °C, from 55 °C to 65 °C, from 60 °C to 62 °C) for a duration of 6 to 24 hours, then at a second higher temperature (e.g., higher than the first temperature by 5 °C to 15 °C, by 5 °C to 10 °C, by 10 °C to 15 °C) to provide coelenterazine.
• a first temperature of about 50 °C to 75 °C (e.g., from 60 °C to 70 °C, from 55 °C to 65 °C, from 60 °C to 62 °C) for a duration of 6 to 24 hours, then at a second higher temperature (e.g., higher than the first temperature by 5 °C to 15 °C, by 5 °C to 10
• the HCl and organic solvent can be removed under reduced pressure to provide a residue, the residue can be washed with organic solvents such as ethyl acetate, then dichloromethane, and hexane.
• the residue can be dried under reduced pressure, at room temperature or up to a temperature of about 50 °C (e.g., 40-45 °C) to provide the final coelenterazine.
• the coelenterazine can be obtained in a yield of 70% or more (e.g., 70 % to 95 %, 70 % to 85 %, 80% to 95%, 80% to 85%, or 80%) at a purity of from 55% to 70% (e.g., 55% to 65%, or 60% to 65%) relative to 4-(5-amino-6-benzylpyrazin-2- yl)phenol.
• the coelenterazine of the present disclosure can be made according to Schemes A, B, and C, below.
• Scheme A illustrates the synthesis of coelenteramine (Intermediate I)
• Scheme B illustrates the synthesis of silyl-protected 1,1- diethoxy-3-(4-hydroxyphenyl)propan-2-one (Intermediate II)
• Scheme C illustrates the coupling of coelenteramine and silyl-protected l,l-diethoxy-3-(4-hydroxyphenyl)propan-2- one to generate coelenterazine.
• the coelenterazine of the present disclosure can be made according to Schemes D, E, and F, below.
• Scheme D illustrates the synthesis of coelenteramine
• Scheme E illustrates the synthesis of 1,1-diethoxy-3-(4- hydroxyphenyl)propan-2-one (14)
• Scheme F illustrates the coupling of coelenteramine and 1,1-diethoxy-3-(4-hydroxyphenyl)propan-2-one (14) to generate coelenterazine (16).
• Scheme D Synthesis of coelenteramine.
• the coelenterazine of the present disclosure can be made according to Schemes G, H, and I, below.
• Scheme G illustrates the synthesis of coelenteramine
• Scheme H illustrates the synthesis of 3-(4-(benzyloxy)phenyl)-2-oxopropanal
• Scheme F illustrates the coupling of coelenteramine and 3-(4-(benzyloxy)phenyl)-2-oxopropanal, and subsequent deprotection of the intermediate product 8-benzyl-2-(4-(benzyloxy)benzyl)-6-(4- hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one, to generate 8-benzyl-2-(4-hydroxybenzyl)- 6-(4-hydroxyphenyl)imidazo[1,2-a]pyrazin-3(7H)-one, coelenterazine (16).
• Scheme G Synthesis of coelenteramine.
• coelenterazine, or salt thereof, made according to the methods of the present disclosure can be incorporated into an absorbent article.
• the present disclosure features an absorbent article, including the coelenterazine, or salt thereof, synthesized by the methods of the present disclosure.
• the chemiluminescent system is configured to produce light upon contact with an aqueous system.
• the aqueous system initiates the chemiluminescence reaction in order to produce light.
• the term“aqueous system” refers to water or water-containing compositions.
• such water-containing compositions are generally in the form of body fluid, such as urine, menses, fecal matter, and so forth.
• the occurrence of the release of bodily fluid (or the fluid itself) is referred to herein as an“insult,” or“liquid insult” or“fluid insult.” Accordingly, the chemiluminescent systems of the present disclosure produce light upon insult of an article in which the system is incorporated.
• the chemiluminescent system includes at least one compound or material that luminesces when contacted with an aqueous system.
• water initiates the chemiluminescence.
• the chemiluminescent system includes two or more materials that luminesce when contacted with an aqueous system. In this embodiment, there are two or more materials that together do not luminesce without the presence of the aqueous system.
• Representative chemiluminescent systems that include two or more materials include bioluminescent systems, such as a system that includes a luciferin and a luciferase.
• Bioluminescence is light that is produced by a chemical reaction that occurs within the body or in the secretions of certain type of organisms. Bioluminescence involves the combination of two types of substances in a light-producing reaction: a luciferin and a luciferase. Luciferin is the compound that actually produces the light, for example, the luciferin can be coelenterazine. Luciferase is an enzyme that catalyzes the reaction. In some cases the luciferase is a protein known as a photoprotein, and the light making process requires a charged ion (e.g., a cation such as calcium) to activate the reaction.
• a charged ion e.g., a cation such as calcium
• Photoprotein is a variant of luciferase in which factors required for light emission (including luciferin and oxygen) are bound together as one unit. Often, the bioluminescence process requires the presence of a substance such as oxygen or adenosine triphosphate (ATP) to initiate the oxidation reaction. The reaction rate for the luciferin is controlled by the luciferase or photoprotein. The luciferin- luciferase reaction can also create byproducts such as inactive oxyluciferin and water.
• factors required for light emission including luciferin and oxygen
• ATP adenosine triphosphate
• Luciferin and luciferase are generic names rather than specific materials.
• the luciferin coelenterazine naturally form
• these various forms are collectively called luciferins.
• dinoflagellates marine planktons
• luciferin that resembles the chlorophyll structure.
• the mechanism of light production through a chemical reaction differentiates bioluminescence from other optical phenomenon such as fluorescence or phosphorescence.
• fluorescent molecules do not emit their own light. They need an external photon source to excite the electrons to a higher energy state. On relaxation from the high energy state to their natural ground state, they release their acquired energy as a light source, but usually at a longer wavelength. Since the excitation and relaxation occurs simultaneously, fluorescent light is seen only when illuminated (excited).
• phosphorescence technically refers to a special case of optically excited light emission where the relaxation from the excited state to ground state, unlike the fluorescence, is not immediate, and the photon emission persists for seconds to minutes after the original excitation.
• bioluminescence and fluorescence are two distinct phenomena.
• a bioluminescent can be an autofluorescent but the reverse is not true for a fluorescent; the latter still requires photon for excitation to emit light.
• a bioluminescent cnidarians or crustaceans or fish can contain a fluorescent protein like Green Fluorescent Protein (GFP) and the light emitted from the bioluminescent would act as photons to excite the GFP.
• GFP Green Fluorescent Protein
• the GFP in turn under relaxed state would emit a light of different wave length (most probably of higher wave length) than the wavelength of the bioluminescent light that it has received as photon.
• the GFP may be excited by a blue light emitted by the bioluminescent (wavelength about 470 nm, or 470 nm) but in turn would emit a green light under its relaxed state (wavelength of about 510 nm to about 520 nm, or 510 nm to 520 nm).
• Bioluminescent systems can be incorporated into fluff pulp compositions, fiber matrices, or absorbent articles in any manner that produces the desired chemiluminescence.
• the fluff pulp composition or absorbent product comprises a luciferin selected from the group consisting of coelenterazine, dinoflagellate luciferin, bacterial luciferin, fungal luciferin, firefly luciferin, and vargulin.
• coelenterazine there are many variants, any of which can be used in the fluff pulp composition.
• coelenterazine consistent with this disclosure comprise one or more of native coelenterazine, methyl coelenterazine, coelenterazine 400a (2-2’(4-dehydroxy)) coelenterazine, coelenterazine e, coelenterazine f, coelenterazine h, coelenterazine i, coelenterazine n, coelenterazine cp, coelenterazine ip, coelenterazine fcp, and coelenterazine hep.
• the coelenterazine may be one or more of native coelenterazine, coelenterazine 400a, methyl coelenterazine, coelenterazine f, coelenterazine cp, coelenterazine fcp, and coelenterazine hep.
• the coelenterazine may be one or more of coelenterazine 400a, methyl coelenterazine and coelenterazine fcp.
• the coelenterazine may be one or more of coelenterazine 400a, methyl coelenterazine, and coelenterazine hep.
• the coelenterazine may be may be one or more of coelenterazine 400a and coelenterazine hep.
• the luciferin has a concentration of 0.0005% to 0.002%, by weight of the fluff pulp. In one embodiment, the luciferin has a concentration of 0.0005% to 0.0015%, by weight of the fluff pulp. In one embodiment, the luciferin has a concentration of 0.0005% to 0.001%, by weight of the fluff pulp.
• the luciferin can be incorporated in any component of an absorbent article.
• the luciferin e.g., coelenterazine, or a coelenterazine salt of the present disclosure
• the luciferin can be incorporated into an absorbent article in an amount of from about 0.01 to about 100 mg (e.g., from about 0.01 to about 75 mg, from about 0.01 to about 50 mg, from about 0.01 to about 25 mg, from about 0.01 to about 10 mg, or from about 0.01 to about 5 mg), or 0.01 to 100 mg (e.g., from 0.01 to 75 mg, from 0.01 to 50 mg, from 0.01 to 25 mg, from 0.01 to 10 mg, or from 0.01 to 5 mg).
• the fluff pulp composition or absorbent product comprises luciferase selected from the group consisting of Gaussia luciferase (Glue), Renilla luciferase (RLuc), dinoflagellate luciferase, firefly luciferase, fungal luciferase, bacterial luciferase, and vargula luciferase.
• luciferase selected from the group consisting of Gaussia luciferase (Glue), Renilla luciferase (RLuc), dinoflagellate luciferase, firefly luciferase, fungal luciferase, bacterial luciferase, and vargula luciferase.
• Certain embodiments of the luciferase consistent with this disclosure comprise one or more of Gaussia luciferase, Renilla luciferase, dinoflagellate luciferase, and firefly
• the luciferase may be one or more of Gaussia luciferase, Renilla luciferase, dinoflagellate luciferase, and firefly luciferase.
• the luciferase may be one or more of Gaussia luciferase and Renilla luciferase.
• the luciferase has a concentration of about 0.005% to about 0.04% (e.g., 0.005% to 0.04%) by weight of the fluff pulp. In one embodiment, the luciferase has a concentration of about 0.005% to about 0.02% (e.g., 0.005% to 0.02%) by weight of the fluff pulp. In one embodiment, the luciferase has a concentration of about 0.005% to about 0.01% (e.g., 0.005% to 0.01%) by weight of the fluff pulp.
• the luciferase can be incorporated in any component of an absorbent article.
• the luciferase e.g., GLuc
• the luciferase can be incorporated into an absorbent article in an amount of from about 0.2 mg to about 40 mg (e.g., from about 0.2 mg to about 30 mg, from about 0.2 mg to about 20 mg, from about 0.2 mg to about 15 mg, from about 0.2 mg to about 10 mg, from about 0.2 mg to about 5 mg, or from about 0.2 to about 2 mg); or from 0.2 mg to 40 mg (e.g., from 0.2 mg to 30 mg, from 0.2 mg to 20 mg, from 0.2 mg to 15 mg, from 0.2 mg to 10 mg, from 0.2 mg to 5 mg, or from 0.2 to 2 mg).
• the chemiluminescent system comprises coelenterazine as the luciferin and Gaussia or Renilla luciferase.
• Representative luciferins include those of the coelenterazine family. Coelenterazine in its native form as well as its analogs have different luminescent characteristics due to variation in their structural moieties. Given structural variations within the coelenterazine family, some are good substrates for certain luciferases, whereas some are not. Below is a brief description of native coelenterazine and representative analogs.
• Coelenterazine (native form) is a luminescent enzyme substrate for Renilla (reniformis) luciferase (Rluc). Renilla luciferase/coelenterazine has also been used as the bioluminescence donor in bioluminescence resonance transfer (BRET) studies.
• Renilla luciferase/coelenterazine has also been used as the bioluminescence donor in bioluminescence resonance transfer (BRET) studies.
• Coelenterazine 400a is a derivative of coelenterazine and is a good substrate for Renilla luciferase, but does not oxidize well with Gaussia luciferase (Gluc). It is the preferred substrate for BRET (bioluminescence resonance energy transfer) because its emission maximum of about 400 nm (e.g., 400 nm) has minimal interference with the GFP emission.
• BRET bioluminescence resonance energy transfer
• Fluorescence resonance energy transfer (FRET), BRET, resonance energy transfer (RET), and electronic energy transfer (EET) are mechanisms describing energy transfer between two light-sensitive molecules (chromophores) and can define the interference of a luminescent chemical with another luminescent chemical’s energy transfer.
• a donor chromophore initially in its electronic excited state, may transfer energy to an acceptor chromophore through nonradiative dipole-dipole coupling.
• the efficiency of this energy transfer is inversely proportional to the sixth power of the distance between donor and acceptor, making FRET extremely sensitive to small changes in distance. Measurements of FRET efficiency can be used to determine if two fluorophores are within a certain distance of each other.
• Such measurements are used as a research tool in fields including biology and chemistry.
• Coelenterazine cp in a coelenterazine-aequorin complex generates luminescence intensity about 15 times (e.g., 15 times) higher than coelenterazine (native form).
• Coelenterazine f has about 20 times (e.g., 20 times) higher luminescence intensity (coelenterazine-apoaequorin complex) than the native form coelenterazine, while its emission maximum is about 8 nm (e.g., 8 nm) longer than that of the native form.
• Coelenterazine fcp is an analog wherein the a-benzene structure in the coelenterazine moiety of coelenterazine f structure is replaced with a cyclic pentane (similar to coelenterazine cp).
• Coelenterazine fcp has luminescence intensity about 135 times (e.g., 135 times) greater than that of coelenterazine (native form).
• Coelenterazine fcp complexes with aequorin to form a coelenterazine fcp-apoaequorin complex and, as a substrate for aequorin, has a relative luminescence intensity of about 135 times (e.g., 135 times) that of native coelenterazine.
• coelenterazine fcp is a poor substrate for Renilla luciferase.
• coelenterazine e as a substrate for Renilla Luciferase enzyme, are coelenterazine e, h and n. While these three analogs are good to excellent substrates for Renilla luciferase, they are poor substrates for apoaequorin.
• the luminescent properties of coelenterazine analogs vary. For example, certain analogs emit less light (as measured as lumens) but with higher luminescent intensity (lumens/steradian). Table A lists the luminescent properties of coelenterazine (native form) and its analogs with Renilla Luciferase. Luminescent intensity is reported as a % initial intensity. For example, an analog having an initial intensity of 900% is about 20 times (e.g., 20 times) intense as compared to the native coelenterazine with an initial intensity of about 45% (e.g., 45%).
• Light is produced by the chemiluminescent system.
• the light is visually detectable by a caregiver in the dark and through clothing, and as such the light has a wavelength, intensity, and duration sufficient to provide the necessary indication.
• These spectral characteristics of the chemiluminescent system can be tailored based on the chemiluminescent compound or compounds. For example, in bioluminescent systems, the luciferin and luciferase can be selected to produce the desired light characteristics. Depending on the bioluminescent system used, different spectral characteristics can occur. In the presence of superoxide anions and/or peroxynitrile compounds, coelenterazine can also emit light independent of enzyme (luciferase) oxidation, a process known as autoluminescence.
• enzyme luciferase
• the chemiluminescent system can be tailored to produce particular colors of light.
• the emission wavelength can range from about 400 nm (violet, e.g., 400 nm) to about 475 nm (blue with green tint, e.g., 475 nm).
• the duration of the light emitted may be controlled by the selection of the coelenterazine (luciferin), in native form versus its analogues, and the enzyme (Luciferase), for example Gaussia versus Renilla.
• the ratio and the concentration of luciferin and luciferase used may also modify the duration of light emission.
• the luciferin analogue, coelenterazine e has a total light of 130% and initial intensity of 900% over native coelenterazine.
• the duration of the light emitted can last as long as about 8 to about 10 hours (e.g., 8 to 10 hours).
• the light has a duration of about 0.5 to about 6 hours (e.g., 0.5 to 6 hours).
• the light has a duration of about 1 to about 4 hours (e.g., 1 to 4 hours).
• the light has a duration of about 2 to about 3 hours (e.g., 2 to 3 hours).
• quantum efficiency of the chemiluminescence contributes to the intensity, depth, and hue of the color of the emission.
• Quantum efficiency is the fraction of photon flux used to excite a luminescence chemical to elevate it to higher energy state. Quantum efficiency is one of the most important parameters used to evaluate the quality of a detector and is often called the“spectral response” to reflect its wavelength dependence. It is defined as the number of signal electrons created per incident photon. In some cases it can exceed 100% (i.e. when more than one electron is created per incident photon). If the spectral response exceeds 100%, then the intensity and depth of the color emitted is vivid, but depending on the status of the excited state of the primary electron, the duration of the emission will be determined (i.e., the higher the excited state, the more time it takes to return to the ground (normal) state).
• Spectral responsivity is a similar measurement, but it has different units; the metric being the amperes or watts (i.e., how much current comes out of the device per incoming photon of a given energy and wavelength).
• Both the quantum efficiency and the spectral responsivity are functions of the photons’ wavelength.
• the luciferin coelenterazine between the native form and one of its analogs, coelenterazine e, the latter has not only high light intensity but emits 30% more light energy than the former, because the latter upon excitation by a given quanta (hv) of incident photon generates two electrons and the primary electron at wavelength 475 has the same emission intensity as native coelenterazine but with lumen intensity about 20 times (e.g., 20 times) greater than that of the native product. Accordingly, the light emitted by the excited coelenterazine analog would be twenty times brighter than the native form but with a total light energy of about 130% (e.g., 130%) will last longer than the native form.
• the wavelength determines the color of the emitted light.
• the fluff pulp composition includes a luciferin and a luciferase.
• a fluff pulp has both elements of the chemiluminescent system required to luminesce upon contact with an aqueous system.
• the fluff pulp composition includes at least one component selected from a luciferin and a luciferase.
• the fluff pulp composition may include only one of a luciferin and a luciferase.
• Such a fluff pulp composition may be incorporated into an absorbent article such that the other one of the luciferin and the luciferase may be disposed in a top sheet or other layer of the absorbent article, such that the two components are combined only when carried by a liquid insult (e.g., water from an aqueous system passing through the top sheet into the fluff pulp composition).
• a liquid insult e.g., water from an aqueous system passing through the top sheet into the fluff pulp composition.
• the fluff pulp composition comprises a luciferin but not a luciferase.
• the fluff pulp composition comprises a luciferase but not a luciferin.
• the fluff pulp of the fluff pulp composition can be formed from any pulp.
• the fluff pulp is derived from a lignocellulosic fiber.
• the fluff pulp is derived from a lignocellulosic fiber derived from wood.
• the fluff pulp is derived from a lignocellulosic fiber derived from wood by chemical, mechanical, chemimechanical, or thermomechanical means.
• the fluff pulp is derived from a cellulosic fiber derived from wood by chemical pulping.
• the fluff pulp is derived from a cellulosic fiber derived from chemical pulping of wood either by alcohol pulping, organo-solve pulping, acid sulfite pulping, alkaline sulfite pulping, neutral sulfite pulping, alkaline peroxide pulping, Kraft pulping, Kraft-AQ pulping, polysulfide pulping, or polysulfide-AQ pulping.
• the fluff pulp is derived from a cellulosic fiber derived from chemical pulping of wood by further removing lignin from the said pulp either by alcohol pulping, organo-solve pulping, acid sulfite pulping, alkaline sulfite pulping, neutral sulfite pulping, alkaline peroxide pulping, Kraft pulping, Kraft-AQ pulping, polysulfide pulping, or polysulfide-AQ pulping for the preparation of absorbent articles (fluff pulp).
• the fluff pulp is derived from a cellulosic fluff pulp derived from Kraft pulping.
• the fluff pulp is derived from a cellulosic bleached fluff pulp derived from Kraft pulping. In one embodiment, the fluff pulp is derived from a cellulosic bleached fluff pulp derived from Kraft pulping of softwoods. In one embodiment, the fluff pulp is derived from a cellulosic bleached fluff pulp derived from Kraft pulping of Southern softwoods. In one embodiment, the fluff pulp is derived from a cellulosic bleached fluff pulp derived from Kraft pulping of Southern pine. In one embodiment, the fluff pulp is derived from a Southern softwood. In one embodiment, the fluff pulp is derived from Southern pine.
• the fluff pulp composition can be produced from pulp in any form, such as a wet-laid sheet which is dried to achieve a moisture content ranging from about 6% to about 11% (e.g., 6% to 11%).
• the fluff pulp composition is prepared by incorporating at least one component of the chemiluminescent system into the fluff pulp.
• fluff pulp can be treated with one or more components of the chemiluminescent system.
• One challenge in the chemical treatment of fluff pulp is to maintain the chemicals in a state in which the intended chemiluminescent reaction is not prematurely triggered, for example, before the treated fluff pulp is incorporated into an absorbent article that is then subjected to a liquid insult.
• the chemicals typically cannot be comingled with water and be applied together.
• either the luciferase or luciferin may be microencapsulated and introduced during the wet-laying process, with the non-encapsulated component applied to the sheet in a non-aqueous environment by standard methods such as coating, dipping, spraying, or printing (or combination thereof), prior to the air-laid operation during absorbent article manufacture.
• a two sheet system one containing luciferase and the other containing luciferin, may be made and processed further before the air-laid operation during absorbent article manufacture.
• one of the chemicals maybe added during the wet-laying process and the other during the subsequent processing of the pulp; or the two components may be added to the pulp during or prior to the air-laid process, such as by rinsing and/or spraying the pulp in fluffed form with non-aqueous solutions of one or both the respective components.
• the fluff pulp composition; the isolated composition including the coelenterazine, or salt thereof; and/or the coelenterazine, or salt thereof can be incorporated into absorbent articles.
• Representative absorbent articles include child diapers, adult diapers, adult incontinence products, feminine hygiene products, absorbent underpads, and wound care dressing articles.
• the fluff pulp composition and/or the coelenterazine, or salt thereof can be incorporated into one or more absorbent layers or portions of an absorbent article.
• an absorbent article is provided.
• the absorbent article includes a top sheet that is liquid permeable, a back sheet that is liquid impermeable, fluff pulp disposed between the top sheet and the back sheet and/or a fluffless or near fluffless non-woven fabric matrix disposed between the top sheet and the back sheet, and a chemiluminescent system configured to produce light upon contact with an aqueous system.
• the chemiluminescent system (e.g., a luciferin such as coelenterazine, or a salt thereof of the present disclosure, and a luciferase) of the absorbent article is as described herein.
• the chemiluminescent system need not be disposed, in whole or in part, within the fluff pulp.
• structural and fluid distribution functions may be provided, in some configurations, by synthetic fibers, leading to the development of absorbent cores containing both fluff pulp fibers and synthetic fibers, and even“fluff-less” absorbent cores containing no fluff pulp fibers.
• the chemiluminescent system, or parts of the chemiluminescent system can be independently integrated in the liquid permeable top sheet, the liquid impermeable back sheet, the SAP, or another structure in the absorbent article.
• the chemiluminescent system comprises a luciferin and a luciferase.
• the luciferin and the luciferase are both disposed within the fluff pulp.
• one of the luciferin and the luciferase is disposed within the fluff pulp and the other is disposed in a different layer (e.g., top sheet or ADL) of the absorbent product such that the two components are combined only when at least one of the two components is carried by a liquid insult (e.g., passing through the top sheet or ADL into the fluff pulp composition).
• the fluff pulp comprises a luciferin but not a luciferase.
• the fluff pulp comprises a luciferase but not a luciferin.
• At least one component of the chemiluminescent system is disposed on (for example, printed onto) the inner surface of the backsheet.
• one of the luciferin and the luciferase is disposed within the fluff pulp and the other is associated with the top sheet or another structure within an article, and configured to travel into the fluff pulp upon exposure to a liquid insult.
• the absorbent article further comprises a pH buffer, as disclosed herein.
• the pH buffer is disposed within the fluff pulp.
• structural and fluid distribution functions may be provided, in some configurations, by synthetic fibers, leading to the development of absorbent cores containing both fluff pulp fibers and synthetic fibers, and even“fluff-less” absorbent cores containing no fluff pulp fibers.
• the chemiluminescent system, or parts of the chemiluminescent system can be independently integrated in the liquid permeable top sheet, the liquid impermeable back sheet, the SAP, or another structure in the absorbent article.
• the absorbent article further comprises a photoluminescent compound, as disclosed herein.
• the photoluminescent compound is disposed within the fluff pulp.
• the absorbent article further comprises a photoluminescent compound and a pH buffer, as disclosed herein.
• the photoluminescent compound and the pH buffer are disposed within the fluff pulp.
• the pH buffer, the photoluminescent compound, the luciferin, and the luciferase are disposed within the fluff pulp.
• At least one of the pH buffer, the photoluminescent compound, the luciferin, and the luciferase are not disposed within the fluff pulp. In some embodiments, at least one of the pH buffer, the photoluminescent compound, the luciferin, and the luciferase can be independently incorporated into synthetic fibers,“fluff-less” absorbent cores containing no fluff pulp fibers, in the liquid permeable top sheet, the liquid impermeable back sheet, and/or the SAP of the absorbent article. In some embodiments, the pH buffer, the photoluminescent compound, the luciferin, and/or the luciferase can migrate to an absorbent core from a different structure of the article. In some embodiments, the pH buffer, the photoluminescent compound, the luciferin, and/or the luciferase can migrate from an absorbent core to a different structure of the article.
• the absorbent article further includes a superabsorbent polymer (SAP), such as incorporated in the absorbent core.
• SAP superabsorbent polymer
• at least one component of the chemiluminescent system may be disposed in the SAP, such that the chemiluminescence is generated upon the fluid from an insult traveling to the absorbent core.
• the chemiluminescent system is contained entirely within an absorbent core of the absorbent article.
• the absorbent core is almost always a multi- component system there exist more than one approach to incorporate the chemiluminescent system into the absorbent core.
• the fluff pulp fibers could be the carrier of the chemiluminescent system.
• the chemiluminescent system could be contained within superabsorbent particles incorporated into the absorbent article.
• the absorbent core can include cellulose fibers, cellulose fiber derivatives (rayon, lyocell, etc.), nonwoven cellulose fibers and/or cellulose fiber derivatives, non-cellulose fibers, or any combination thereof.
• SAP particles or fibers contained the chemiluminescent system chemistry, a desired pattern, such as an aesthetically pleasing pattern, can be achieved.
• the chemiluminescent system can be added to the fluff pulp fibers at the time of absorbent article manufacture or during an upstream process entirely separated from final product assembly. As noted above, for example, the chemiluminescent system may be sprayed onto or otherwise incorporated into a fluff pulp sheet prior to hammermilling.
• absorbent articles are also provided.
• Absorbent articles are manufactured according to general techniques known to those of skill in the art that allow the incorporation of the chemiluminescent system to be incorporated into the absorbent article in the manner disclosed herein.
• Example 1 describes the synthesis of coelenterazine on a 1 Kg scale.
• Example 2 describes the synthesis of coelenterazine on a 25 gram scale.
• Example 3 describes the synthesis of coelenterazine on a 100 gram scale.
• Example 4 describes the synthesis of coelenterazine on a multi-kilogram scale.
• the mixture was cooled to 40 °C and charged with water (13 L) and ethyl acetate (15 L) at 35-40 °C.
• the reaction mixture was stirred for 20 minutes.
• the ethyl acetate layer was separated, and the aqueous layer was re- extracted with ethyl acetate (3L x 2).
• the combined ethyl acetate extracts were concentrated under reduced pressure.
• the residue was taken up with 2L of ethyl acetate and refluxed.
• the solution was slowly cooled to 10-15 °C and the solid formed was filtered to yield the desired product. Yield 90%-95%. Purity 90%.
• the product can be optionally purified by charging 1 Kg of the product and 5 L 1,4-dioxane at room temperature into a 10L round bottom flask, adding sodium hydroxide solution (250g sodium hydroxide in 1L water) to the solution, charging the flask with 100g of charcoal and 100g silica gel at room temperature, stirring the mixture at room temperature for 20 mins, and filtering and washing the solids with 250 ml 1,4-dioxane. The filtrate was then transferred to another 20.0 L round bottom flask and 200 ml HCl slowly added to the reaction mixture to adjust the pH to 7 to 7.5 at room temperature, during which a solid precipitate was observed.
• sodium hydroxide solution 250g sodium hydroxide in 1L water
• reaction mixture was then stirred at room temperature for 30 mins, filtered, and washed with 200 ml 1,4-dioxane.
• the isolated solid product was dried under vacuum, and in in the oven at 50-55°C for 4 hrs. Yield 90%-95%. Purity 90%.
• 1,4-bis(diphenylphosphino)butane (2.71 g, 6.34 mmol) was added to a suspension of bis(benzonitrile)dichloropalladium (II) (2.03 g, 5.29 mmol) in toluene (210 mL) at room temperature under an argon atmosphere and stirred for 30 minutes.
• a solution of 3-benzyl-5- bromopyrazin-2-amine (2) (28.0 g, 106.0 mmol) in toluene (180 mL) was added to this mixture followed by 4-methoxyphenylboronic acid (20.94 g, 137.8 mmol), ethanol (42 mL), and 1.0 M aq.
• Cyanuric chloride (1.0 g) was added to anhydrous N,N’-dimethylformamide (5ml) at room temperature under an atmosphere of argon and stirred for 30 minutes. A white suspension was formed. A solution of (4-(benzyloxy)phenyl)methanol (1.0 g) in dichloromethane (30ml) was added and stirred overnight. The precipitated solids were removed by filtration. The filtrate was diluted with hexane (50 ml) and washed with water, brine solution (20 ml each), dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure.
• Methanesulfonyl chloride (13.74 g; 0.12 mol) was added dropwise to a solution of (4- (benzyloxy)phenyl)methanol (21.8 g; 0.10 mol) and triethylamine (15.15 g; 0.15 mol) in dichloromethane (250 ml) at 0 o C. After the addition the reaction mixture was warmed to room temperature and stirred 12 h. The solvent was removed under reduced pressure. The residue was partitioned between ethyl acetate (200ml) and water (100ml). The ethyl acetate layer was separated, washed with water, brine solution (75 ml each), dried over anhydrous magnesium sulfate.
• Mg turnings (10.57g, 0.435 mole, 1.5 equiv) were suspended in dry distilled THF (100 mL) in an argon-flushed, 500 mL two necked round-bottom flask.
• a solution of (11) (68.14 g, 0.29 mole) in THF (600 ml) was prepared and 25 ml of the solution was added at once and the flask was warmed to 40-50 °C with constant stirring until the Grignard reaction was initiated. After the initiation the remaining solution was added slowly at a rate so that the reaction mixture was warm to touch due to the heat of the reaction. After the addition mixture was stirred at room temperature for 30 min and then refluxed for 1 hour to complete the reaction.
• the pale yellow Grignard reagent was allowed to cool to room temperature and was then kept in an ice bath.
• the Grignard reagent was transferred to dropping funnel and was added drop wise into the cooled flask over 45 min. The mixture was then stirred for 6 h at–78 °C and warmed to -20 °C and stirred for 2 h.
• the reaction was quenched with saturated ammonium chloride solution (200 mL).
• the reaction mixture was extracted with ethyl acetate (500 mL).
• reaction mixture was analyzed by reverse phase HPLC.
• An authentic coelenterazine sample was used to identify the desired product.
• reaction mixture was analyzed by reverse phase HPLC.
• An authentic Coelenterazine sample was used to identify the desired product.
• 1,4-dioxane (2.3 mL), water (225 ⁇ L), and conc. HCl (225 ⁇ L) taken in a 25 ml round bottomed flask was degassed and filled with argon.4-(5-amino-6-benzyl-pyrazin-2-yl)phenol ((7), 441 mg, 1.59 mmol) was added to this mixture.
• argon.4-(5-amino-6-benzyl-pyrazin-2-yl)phenol ((7), 441 mg, 1.59 mmol) was added to this mixture.
• a solution of 1,1-diethoxy-3-(4- hydroxyphenyl)-2-propan-2-one) ((14), 493 mg, 2.06 mmol, 1.3 eq) in 1,4- dioxane (2 mL) was added to this mixture.
• the resulting mixture was degassed and stirred under argon atmosphere at 78-82 °C for 14 hr.
• the dark brown solution was cooled to room temperature, and an aliquot was analyzed by reverse phase HPLC.
• the HPLC analysis indicated that the reaction mixture had little starting material.
• the reaction was degassed, and heating was continued for further 6 h (total 20 h).
• the reaction mixture was cooled to room temperature, and concentrated under reduced pressure.
• the dark brown residue was dried under high vacuum overnight. Ethyl acetate (40 mL) was added to the residue and triturated. The solid was allowed to settle decanted, and dried under vacuum to yield brown dry powder.
• 1,4-dioxane 80.0 mL
• water 9.1 mL
• conc. HCl 9.1 mL
• argon.4-(5-amino-6-benzyl-pyrazin-2-yl)phenol 7, 15.94 g, 59.93 mmol
• a degassed 1,4-dioxane (71 mL) solution of 1,1-diethoxy-3-(4-hydroxyphenyl)-2-propan-2-one) 14, 16.4 g, 68.82 mmol, 1.2 eq
• a 100 L round bottom flask was charged with 7.5 L of THF, 2.5 kg of magnesium metal, 10 g of iodine, and 200 ml ethyl bromide.
• the reaction mass was initiated.
• benzyl chloride in THF solution (10 L benzyl chloride dissolved in 45 L of THF) was slowly added at 20-25 °C over a period of 4 to 4.5 hours and thereafter maintained for one hour at 30 - 35 °C.
• 2-amino pyrazine solution 2.5 kg 2-amino pyrazine dissolved in 25L THF at 30-35 °C in 1 to 1.5 hours was slowly added and the reaction mass was maintained for 5-6 hours at 30-35 °C.
• the present modification reduces or eliminates the use of: n-butyl lithium-in the first step of the synthesis of Example 1, where n-butyl lithium reaction in toluene has been replaced by reaction with benzyl chloride and THF (tetrahydrofuran).
• the present Example improves the ability to scale up the reaction chemistry and reduces the cost of the synthesis.
• the changes improve the overall safety of the chemistry by replacing highly reactive materials with more stable materials.
• the present example omits the use of boronic acid compounds in the synthesis, and greatly reduces the amount of expensive palladium catalyst in the reaction.
• a 50L round bottom flask was charged with magnesium turnings (1Kg) and anhydrous tetrahydrofuran (3L) followed by iodine (10 g) and dibromoethane (50 mL).
• a solution of tert- butyl(4-(chloromethyl)phenoxy)dimethylsilane (21) (1.6 kg) in anhydrous tetrahydrofuran (12 L) was added drop wise at 40-45 °C over a period of 4 hours. The reaction mixture was cooled to 35 °C.
• Another 50 L round bottomed flask was charged with methyl 2,2-dimethoxyacetate (1.2 kg) and anhydrous tetrahydrofuran (10 L) and cooled to 30-35 °C.
• Example 5 LC-MS Characterization of Isolated Coelenterazine Compositions
• the relative amount of coelenterazine to 4-(5-amino-6-benzylpyrazin-2-yl)phenol (7) (coelenteramine) in the final isolated composition from the final coupling reaction to form coelenterazine in Examples 1-3 can be assessed by liquid chromatography-mass spectrometry (LC-MS).
• the diluted solution including the isolated coelenterazine composition was separated by LC on a C-18 reverse phase column using a gradient elution.
• the separation provided a response for coelenterazine at about 1.7 min and a response for coelenteramine (7) at about 2.5 min.
• Tandem MS was configured to monitor the (M+H)+ parent ion of each compound which was subsequently fragmented into its characteristic daughter ion. The daughter ion intensity created the chromatographic signal for each compound which was then integrated to produce an area for the signal.
• the parent ion for coelenterazine is 424.1 Da with a daughter ion at 302.2 Da.
• the parent ion for coelenteramine is 278.1 Da and its daughter was 132.0 Da.
• Table 4 the ratio of the coelenterazine to coelenteramine in the isolated composition was between about 24:1 and 80:1. Table 4. Integrated peak ratios of coelenterazine to coelenteramine as assessed by LC-MS.
• reaction mass was then allowed to settle for 30 mins.
• the THF layer was separated and distilled out completely under vacuum below 70 °C.
• the reaction mass was then cooled to room temperature and charged with 20 L toluene and 5 L water and stirred for 10 minutes.
• the reaction mass was then allowed to settle for 20 minutes and the toluene layer was separated.
• the toluene layer was then charged with 3L HC1 and allowed to settle for 10 minutes. Then the toluene layer was separated and kept aside.
• the acidic HC1 layer was then adjusted to a pH of about 8-9 with 3 kg soda ash and maintained for 30 minutes.
• the organic layer was then separated to yield the desired mono alkylated product in 45-50% yield, at a purity 90-95%.
• the ethyl acetate layer was separated, and the aqueous layer was re-extracted with ethyl acetate (3 L x 2).
• the combined ethyl acetate extracts were adjusted to pH 7-7.5 with soda-ash and was concentrated under reduced pressure.
• the residue was first cooled to 40 oC and was then taken up with 4L of cyclohexane and refluxed.
• the compound was filtered through Nutsche filter and dried at 40-45 oC for 5-6 hrs. Yield: 75– 80 % Purity: 90%.
• the ethyl acetate layer was separated and this layer was washed with a soda-ash solution ( 1Kg soda-ash in 4L water) to adjust the pH of the layer to 8-9. The mixture was stirred for 10 minutes. The ethyl acetate layer was separated again and was washed with a solution of common salt. (1Kg NaCl in 3L water). The mixture was stirred for 10 minutes. The ethyl acetate layer was separated once again and was concentrated under reduced pressure. The residue was taken up with n-hexane (10L) and was refluxed. The product was then cooled to 10 oC and was stirred for 30 minutes.
• a soda-ash solution 1Kg soda-ash in 4L water

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