The 4-position Of The Hetero Ring Is Unsubstituted Or Alkyl Substituted Only Patents (Class 540/362)
  • Patent number: 5300509
    Abstract: Compounds of formula I, and pharmaceutically acceptable salts thereof, ##STR1## in which R1 is hydrogen (1-6C)alkyl or (1-4C)alkanoyl;A is --N.dbd.CQ--O--, N.dbd.CQ--NR.sup.8 --, --N.dbd.CQ--CH.dbd.N--or --N.dbd.CH--CQ.dbd.N--;Q is 2-furyl;R.sup.8 is hydrogen or C1-4C)alkyl;and R.sup.2 has any of the meanings given in the specification, processes for preparing the compounds and pharmaceutical compositions containing them. The compounds are useful as adenosine antagonists.
    Type: Grant
    Filed: November 20, 1992
    Date of Patent: April 5, 1994
    Assignee: Imperial Chemical Industries PLC
    Inventors: Michael H. Block, Alison Harrison, Rodney B. Hargreaves
  • Patent number: 5296595
    Abstract: A chiral catalyst is disclosed together with methods of using it for enantioselective syntheses. The chiral catalyst includes a nucleus with two metal atoms that has four bridging ligands oriented radially to the axis of the nucleus. Each of these ligands includes a two complexing atoms each complexed to one of the metal atoms. At least one of the bridging ligands includes a chiral center which is bonded to one of the complexing atoms. Preferably, all four of the bridging ligands include a chiral center bonded to one of the complexing atoms. The catalyst of the invention has been found to be useful in catalyzing carbenoid transformation reactions such as cyclopropanation.
    Type: Grant
    Filed: September 24, 1992
    Date of Patent: March 22, 1994
    Assignee: Research Corporation Technologies
    Inventor: Michael P. Doyle
  • Patent number: 5284857
    Abstract: Substituted thienopyrans and processes for preparing the thienopyrans are disclosed. The thienopyrans are useful as antihypertensive agents; antianginals are peripheral antivasoconstrictive agents.
    Type: Grant
    Filed: December 21, 1990
    Date of Patent: February 8, 1994
    Assignee: Ortho Pharmaceutical Corporation
    Inventors: Jeffery B. Press, Pauline Sanfilippo, James J. McNally, Robert Falotico
  • Patent number: 5250677
    Abstract: The present invention relates to new 3-guanidinoalkyl-2-azetidinones of the formula ##STR1## wherein: U and W can be the same or different and are selected from the group consisting of hydrogen and an amino protecting group;n is 1 to 3;X is a member selected from the group consisting of hydrogen, trialkylsilyl, arylsulfonyl, amino substituted arylsulfonyl, alkylsulfonyl, arylaminocarbonyl, alkylcarbonyl and arylcarbonyl; andY is a member selected from the group consisting of hydrogen, arylalkenyl, arylalkyl, formyl, carboxy, alkoxycarbonyl, acyloxy, arylthio, arylsulfinyl, arylsulfonyl, alkylthio, alkylsulfinyl, alkylsulfonyl, arylaminocarbonyl, the radical ##STR2## in which R is hydrogen, alkyl or arylalkyl, and the radical ##STR3## in which m is 1 to 3 and R' is hydrogen or --CO.sub.2 R" wherein R" is hydrogen, alkyl or arylalkyl.The novel azetidinones of the present invention exhibit anti-thrombin and anti-trypsin activities and are thus useful in controlling blood coagulation and treating pancreatitis.
    Type: Grant
    Filed: October 6, 1992
    Date of Patent: October 5, 1993
    Assignee: Bristol-Myers Squibb Company
    Inventor: William T. Han
  • Patent number: 5250676
    Abstract: Provided is a process for diastereoselectively preparing compounds of the formula ##STR1## which includes the step of subjecting a compound of the formula ##STR2## to a salt whose anion is a nucleophilic base whose conjugate acid has a pKa in the range of between about -7 to about 14, or a silylated derivative of the salt; whereinR.sub.1 is said nucleophile;R is hydrogen, or protected amino,R.sub.2 is R.sub.4 as defined herein below;R.sub.3 is a leaving group; andR.sub.4 is hydrogen, C.sub.1 -C.sub.6 alkyl, or a group of the formula--CH.sub.2 --CH.sub.2 --R.sub.6whereinR.sub.6 is 2-furyl, naphthyl, phenyl, phenyl substituted with 1, 2 or 3 substituents selected from C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 alkylthio, nitro, halo, carboxy and amido; orR.sub.6 is a group of the formula--COOR.sub.7or--COSR.sub.7in whichR.sub.7 is selected from C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl, benzyl, phenyl, or benzyl or phenyl substituted with 1, 2 or 3 substituents selected from C.sub.
    Type: Grant
    Filed: March 23, 1992
    Date of Patent: October 5, 1993
    Assignee: University of Notre Dame du Lac
    Inventors: Catherine M. Gasparski, Marvin J. Miller, Min Teng
  • Patent number: 5241064
    Abstract: Preparation of optically active 3-substituted azetidinones of the formula (I) ##STR1## in which R.sup.1 is a hydroxy-protective group wherein an allylic alcohol of the formula (II) ##STR2## is acylated, then subjected to asymmetric enzymatic hydrolysis yielding the R-allylic alcohol. The hydroxyl group is protected and then stereoselectively reacted with an amine which is subsequently cyclized to yield the desired 3-substituted azetidinone. Two new species of microorganisms have been isolated, Pimelobacter sp. No. 1254 and Bacillus megaterium No. 1253 which exhibit stereoselective esterase activity.
    Type: Grant
    Filed: September 24, 1990
    Date of Patent: August 31, 1993
    Assignee: Fujisawa Pharmaceutical Co., Ltd.
    Inventors: Masayoshi Murata, Toshiyuki Chiba, Fumiyuki Shirai, Kenichi Washizuka, Motohiro Hino
  • Patent number: 5229381
    Abstract: New substituted azetidinones of the general formula (A') which have been found to be potent elastase inhibitors and thereby useful anti-inflammatory and antidegenerative agents are described.
    Type: Grant
    Filed: September 20, 1991
    Date of Patent: July 20, 1993
    Assignee: Merck & Co., Inc.
    Inventors: James B. Doherty, Conrad P. Dorn, Paul E. Finke, William K. Hagmann, Malcolm MacCoss, Shrenik K. Shah
  • Patent number: 5204461
    Abstract: A process for preparing (1'R,3S)-3-(1'-hydroxyethyl)-azetidin-2-one or a derivative thereof represented by formula (I): ##STR1## wherein R.sup.1 represents a hydrogen atom or a hydroxyl-protective group, is disclosed, comprising reacting (2S,3R)-2-aminomethyl-3-hydroxybutyric acid or a derivative thereof represented by formula (II): ##STR2## wherein R.sup.1 is as defined above, with a sulfenamide represented by formula (III): ##STR3## wherein R.sup.2 represents ##STR4## and R.sup.3 and R.sup.4 each represent a hydrogen atom or a cyclic or acyclic hydrocarbon group, provided that they do not simultaneously represent a hydrogen atom, or R.sup.3 and R.sup.4 are taken together with the adjacent nitrogen atom to form a heterocyclic group, and triphenylphosphine. The reaction yield is high, and the sulfenamide (III) used as a lactamization reagent is cheap and can be recovered after the reaction.
    Type: Grant
    Filed: November 8, 1991
    Date of Patent: April 20, 1993
    Assignee: Takasago International Corporation
    Inventors: Toshiyuki Murayama, Takashi Miura, Toyohiko Kobayashi
  • Patent number: 5202433
    Abstract: A polysaccharide derivative prepared by replacing a part or the whole of hydrogen atoms of hydroxyl and/or amino groups of a polysaccharide with one or more atomic groups represented by the following formula (1), (2) or (3) is new and useful for the separation of optical isomers: ##STR1## wherein the number of carbon atoms constituting R is 1 to 30 and R is a group having at least one asymmetric center.
    Type: Grant
    Filed: January 18, 1991
    Date of Patent: April 13, 1993
    Assignee: Daicel Chemical Industries, Ltd.
    Inventors: Yoshio Okamoto, Koichi Hatada
  • Patent number: 5196415
    Abstract: This invention is in the field of clinical neurology and relates specifically to compounds, compositions and methods for treatment of patients with generalized epilepsy or partial (symptomatic) epilepsy using compounds of the formula: ##STR1## This invention also relates to compounds, compositions and methods of treatment for drug craving in patients addicted to cocaine.
    Type: Grant
    Filed: January 29, 1992
    Date of Patent: March 23, 1993
    Assignee: The United States of America as represented by the Department of Health and Human Services
    Inventors: James A. Monn, Andrew Thurkauf, Shunichi Yamaguchi, Michael A. Rogawski, Kenner C. Rice, Mariena V. Mattson, Arthur E. Jacobson
  • Patent number: 5175283
    Abstract: The present invention relates to new 3-guanidinoalkyl-2-azetidinones of the formula ##STR1## wherein: U and W can be the same or different and are selected from the group consisting of hydrogen and an amino protecting group;n is 1 to 3;X is a member selected from the group consisting of hydrogen, trialkylsilyl, arylsulfonyl, amino substituted arylsulfonyl, alkylsulfonyl, arylaminocarbonyl, alkylcarbonyl and arylcarbonyl; andY is a member selected from the group consisting of hydrogen, arylalkenyl, arylalkyl, formyl, carboxy, alkoxycarbonyl, acyloxy, arylthio, arylsulfinyl, arylsulfonyl, alkylthio, alkylsulfinyl, alkylsulfonyl, arylaminocarbonyl, the radical ##STR2## in which R is hydrogen, alkyl or arylalkyl, and the radical ##STR3## in which m is 1 to 3 and R' is hydrogen or --CO.sub.2 R" wherein R" is hydrogen, alkyl or arylalkyl.The novel azetidinones of the present invention exhibit anti-thrombin and anti-trypsin activities and are thus useful in controlling blood coagulation and treating pancreatitis.
    Type: Grant
    Filed: February 11, 1992
    Date of Patent: December 29, 1992
    Assignee: Bristol-Myers Squibb Company
    Inventor: William T. Han
  • Patent number: 5116971
    Abstract: The invention relates to new 1,4-diazepines of the general formula ##STR1## in which R.sub.1, R.sub.2 R.sub.3, X and A have the meaning indicated in the specification.The new compounds are intended for use for the treatment of pathological states and diseases in which PAF (platelet activating factor) is involved.
    Type: Grant
    Filed: September 19, 1990
    Date of Patent: May 26, 1992
    Assignee: Boehringer Ingelheim KG
    Inventors: Albrecht Harreus, Karl-Heinz Weber, Werner Stransky, Gerhard Walther, Gojko Muacevic, Jorge C. Stenzel, Wolf-Dietrich Bechtel
  • Patent number: 5112966
    Abstract: A beta-lactam compound of the formula: ##STR1## wherein R.sub.1 is a hydrogen atom, a lower alkyl group or a 1-hydroxy(lower)alkyl group wherein the hydroxyl group is optionally protected, R.sub.2 is a hydrogen atom or a protective group for the nitrogen atom and R.sub.3 is a methyl group, a halomethyl group, a hydroxymethyl group, a protected hydroxymethyl group, a formyl group, a carboxyl group, a lower alkoxycarbonyl group or an ar(lower)alkoxycarbonyl group wherein the aryl group is optionally substituted, or R.sub.2 and R.sub.3 are combined together to form an oxaalkylene group and, when taken together with one nitrogen atom and two carbon atoms adjacent thereto, they represent a six-membered cyclic aminoacetal group, which is useful as a valuable intermediate in the stereospecific production of 1-methylcarbapenem compounds.
    Type: Grant
    Filed: October 31, 1985
    Date of Patent: May 12, 1992
    Assignee: Sumitomo Pharmaceuticals Company, Limited
    Inventors: Makoto Sunagawa, Haruki Matsumura, Tsuneo Yano, Akira Sasaki, Shinzi Takata
  • Patent number: 5106475
    Abstract: A process for preparing 3-4-cis-.beta.,.beta.-(4)-substituted and 3-4-trans,.beta.,.alpha.-(4)-substituted azetidinones is provided. Also provided are novel 4,4-disubstituted azetidinones.
    Type: Grant
    Filed: October 16, 1990
    Date of Patent: April 21, 1992
    Assignee: Eli Lilly and Company
    Inventors: John M. Morin, Jr., Robert J. Ternansky, David A. Hall
  • Patent number: 5037819
    Abstract: The present invention relates to new 3-guanidinoalkyl-2-azetidinones of the formula ##STR1## wherein: U and W can be the same or different and are selected from the group consisting of hydrogen and an amino protecting group;n is 1 to 3;X is a member selected from the group consisting of hydrogen, trialkylsilyl, arylsulfonyl, amino substituted arylsulfonyl, alkylsulfonyl, arylaminocarbonyl, alkylcarbonyl and arylcarbonyl; andY is a member selected from the group consisting of hydrogen, arylalkenyl, arylalkyl, formyl, carboxy, alkoxycarbonyl, acyloxy, arylthio, arylsulfinyl, arylsulfonyl, alkylthio, alkylsulfinyl, alkylsulfonyl, arylaminocarbonyl, the radical ##STR2## in which R is hydrogen, alkyl or arylalkyl, and the radical ##STR3## in which m is 1 to 3 and R' is hydrogen or --CO.sub.2 R" wherein R" is hydrogen, alkyl or arylalkyl.The novel azetidinones of the present invention exhibit anti-thrombin and anti-trypsin activities and are thus useful in controlling blood coagulation and treating pancreatitis.
    Type: Grant
    Filed: June 4, 1990
    Date of Patent: August 6, 1991
    Assignee: Bristol-Myers Squibb Company
    Inventor: William T. Han
  • Patent number: 4994450
    Abstract: A compound, or a solvate or salt thereof, of formula (I) ##STR1## in which: R.sub.1 and R.sub.2 are independently hydrogen, C.sub.1-6 alkyl, C.sub.2-6 alkenyl, C.sub.3-6 cycloalkyl or C.sub.4-12 cycloalkylalkyl groups, or together form a C.sub.2-8 branched or linear polymethylene or C.sub.2-6 alkenylene group optionally substituted with a hetero-atom, provided that R.sub.1 and R.sub.2 are not simultaneously hydrogen;R.sub.3 is hydrogen, C.sub.1-6 alkyl, preferably methyl or ethyl, or phenyl, or R.sub.3 together with R.sub.1 form a --(CH.sub.2).sub.3 -- or --(CH.sub.2).sub.4 -- group;p is 1, 2, 3 or 4, andR is a group of formula (II) ##STR2## in which the group --(CHR.sub.4).sub.n --X-- is in the meta- or para-position with respect to YR.sub.5 or R.sub.6, R.sub.4 is hydrogen or C.sub.1-6 alkyl, preferably hydrogen;n is 0, 1 or 2, preferably 1;X is a direct bond, or O, S or NR.sub.a in which R.sub.a is hydrogen or C.sub.1-6 alkyl, and is preferably a direct bond;Y is >C.dbd.O, >CHOH, --S.dbd.O or --SO.
    Type: Grant
    Filed: February 10, 1989
    Date of Patent: February 19, 1991
    Assignee: Dr. Lo. Zambeletti S.p.A.
    Inventors: Vittorio Vecchietti, Antonio Giordani
  • Patent number: 4992545
    Abstract: A process for preparing 3-4-cis-.beta.,.beta.-(4)-substituted and 3-4-trans,.beta.,.alpha.- (4)-substituted azetidinones is provided. Also provided are novel 4,4-disubstituted azetidinones.
    Type: Grant
    Filed: September 20, 1989
    Date of Patent: February 12, 1991
    Assignee: Eli Lilly and Company
    Inventors: David A. Hall, deceased, John M. Morin, Jr., Robert J. Ternansky
  • Patent number: 4992435
    Abstract: Substituted thienopyrans and processes for preparing the thienopyrans are disclosed. The thienopyrans are useful as antihypertensive agents; antianginals are peripheral antivasoconstrictive agents.
    Type: Grant
    Filed: September 23, 1988
    Date of Patent: February 12, 1991
    Assignee: Ortho Pharmaceutical Corporation
    Inventors: Jeffery B. Press, Pauline Sanfilippo, James J. McNally, Robert Falotico
  • Patent number: 4981992
    Abstract: A process for preparing an optically active 3-hydroxybutanoic acid represented by formula (I): ##STR1## wherein: R.sup.1 represents a protective group of carboxylic acid, andR.sup.2 represents a hydrogen atom; a lower alkyl group which may be substituted with a halogen atom; a lower alkoxy group; a phenyl group which may be substituted with a lower alkyl group or a lower alkoxy group; or a benzyloxy group which may be substituted with a lower alkyl group or a lower alkoxy group,is disclosed, comprising asymmetrically hydrogenating a 3-oxobutanoic acid ester represented by formula (II): ##STR2## wherein R.sup.1 and R.sup.2 are as defined above, in the presence of a ruthenium-optically active phosphine complex as a catalyst. The compound of formula (I) which is useful for synthesizing a 4-acetoxyazetidin-2-one derivative, a useful intermediate for obtaining penem antibiotics, can be prepared economically.
    Type: Grant
    Filed: November 14, 1989
    Date of Patent: January 1, 1991
    Assignee: Takasago International Corporation
    Inventors: Noboru Sayo, Takao Saito, Yoshiki Okeda, Hiroyuki Nagashima, Hidonori Kumobayashi
  • Patent number: 4939133
    Abstract: The present invention relates to novel N-substituted 2-hydroxybenzamide and N-substituted 2-hydroxy-.alpha.-oxo-benezene acetamide compounds pharmaceutical compositions, and methods of use for therefore for the treatment of diseases in which products having lipoxygenase enzyme activity contribute to the pathological condition. Selected novel intermediates are also the present invention.
    Type: Grant
    Filed: October 1, 1985
    Date of Patent: July 3, 1990
    Assignee: Warner-Lambert Company
    Inventors: David T. Connor, Daniel L. Flynn, Wiaczeslaw A. Cetenko, Jagadish C. Sircar, Charles F. Schwender, Elizabeth A. Johnson, Roderick J. Sorenson, Paul C. Unangst
  • Patent number: 4886890
    Abstract: This invention relates to quaternary compounds having the formula ##STR1## wherein W.sup.- is an anion; m and n are integers having a value of from 1 to 4; R is alkylene having from 3 to 8 carbon atoms; R.sub.1 is a radical having from 8 to 25 carbon atoms and is selected from the group of alkyl, alkenyl and alkoxy alkylene and each of R.sub.2, R.sub.3 and R.sub.4 is a radical having from 1 to 25 carbon atoms and is alkyl, alkoxy or ##STR2## where p has a value of from 1 to 4 and X is hydrogen or methyl. The invention also relates to the preparation and use of said diquaternized compounds.
    Type: Grant
    Filed: September 29, 1988
    Date of Patent: December 12, 1989
    Assignee: GAF Corporation
    Inventors: Ratan K. Chaudhuri, David J. Tracy, Robert B. Login
  • Patent number: 4834846
    Abstract: This invention relates to a process for preparing .beta.-lactams by electrochemically deblocking N-substituting .beta.-lactams using anodic oxidation.
    Type: Grant
    Filed: December 7, 1987
    Date of Patent: May 30, 1989
    Assignee: Merck & Co., Inc.
    Inventors: Newton L. Abramson, Sandor Karady, Edward G. Corley, Leonard M. Weinstock
  • Patent number: 4795809
    Abstract: A compound having the formula (I): ##STR1## is described, together with salts thereof and an enzymatic process for converting such compounds into clavulanic acid.A process for the preparation of the compound of formula (I) and its salts is disclosed, together with intermediates for use therein. This process involves the use of a novel enzyme system to effect the desired cyclization, which enzyme system is preferably derived from a micro-organism, in particular a species of Streptomyces.
    Type: Grant
    Filed: August 27, 1986
    Date of Patent: January 3, 1989
    Assignee: Beecham Group plc
    Inventors: Stefan R. Woroniecki, Stephen W. Elson, Keith H. Baggaley
  • Patent number: 4719207
    Abstract: Substituted azetidinone compounds are provided which have the formula: ##STR1## wherein one of R.sup.1 and R.sup.2 represents a substituted lower alkyl group, an azido group, an amino group, a lower acylamino group, a mercapto group or a lower alkylthio group and the other represents a hydrogen group, or, both represent hydrogen atoms or lower alkyl groups; R.sup.3 represents a hydrogen atom or a group shown by formula: ##STR2## (wherein X represents ##STR3## (wherein R.sup.5 represents a hydrogen atom or a lower alkyl group) and Y represents a hydroxy group, a lower alkoxy group, an amino group, a mono- or di-lower alkylamino group); R.sup.4 represents a hydrogen atom, a substituted or unsubstituted lower alkyl group or a group shown by formula: --CH.sub.2 CO--A (wherein A represents an amino group or a group shown by formula: ##STR4## (wherein X and Y are as defined above), provided that when R.sup.1 and R.sup.2 are both hydrogen atoms, at least R.sup.
    Type: Grant
    Filed: June 20, 1985
    Date of Patent: January 12, 1988
    Assignee: Yamanouchi Pharmaceutical Co., Ltd.
    Inventors: Toshinari Tamura, Makoto Yoshida, Shin-ichi Tsukamoto, Hidenori Iwamoto, Minoru Yamamoto, Soichi Kagami
  • Patent number: 4683303
    Abstract: Novel process for the preparation of azetidin-2-ones of the formula ##STR1## wherein R.sup.1 and R.sup.2 independently from each other are hydrogen, or an organic group linked to the ring carbon via a carbon atom, a nitrogen atom or an oxygen atom, characterized in that a corresponding 4-acyloxyazetidin-2-one, which is substituted by a group --O--CO--R.sup.3 at the 4-position, wherein R.sup.3 is hydrogen or an organic radical stable at the reaction conditions, is reacted with a complex metal hydride comprising reactive hydride ions, such as, lithium borohydride, sodium borohydride, potassium borohydride, zinc borohydride or tetraorganoammonium borohydride.
    Type: Grant
    Filed: October 30, 1984
    Date of Patent: July 28, 1987
    Inventor: Hans R. Pfaendler
  • Patent number: 4680391
    Abstract: New substituted azetidinones are found to be potent elastase inhibitors and thereby useful anti-inflammatory/antidegenerative agents.
    Type: Grant
    Filed: April 10, 1985
    Date of Patent: July 14, 1987
    Assignee: Merck & Co., Inc.
    Inventors: Raymond A. Firestone, Peter L. Barker
  • Patent number: 4652563
    Abstract: This invention relates to dihydropyridazinone compounds having a cyclopropylmethoxyethyl group in the 6-substituent. These compounds are vasodilators and .beta.-adrenoceptor antagonists. A particular compound of the invention is 6-[4-[3-[2-hydroxy-3-[4-(2-(cyclopropylmethoxy) ethyl)phenoxy]propylamino]propionamido]phenyl]-5-methyl-4,5-dihydro-3 (2H)-pyridazinone.
    Type: Grant
    Filed: May 16, 1985
    Date of Patent: March 24, 1987
    Assignee: Smith Kline & French Laboratories Ltd.
    Inventor: Robert A. Slater
  • Patent number: 4629495
    Abstract: Herbicidal compounds of the formula: ##STR1## wherein A represents R.sup.1 R.sup.2 N-- (wherein R.sup.1 represents C.sub.1-8 alkyl or C.sub.2-8 alkenyl or alkynyl unsubstituted or substituted by CN, OH, C.sub.1-6 alkoxy, carboxy, C.sub.2-9 alkoxycarbonyl, aminocarbonyl optionally substituted by C.sub.1-8 alkyl or C.sub.2-8 alkenyl, C.sub.1-8 alkoxyaminocarbonyl, C.sub.1-8 alkanesulphonamidocarbonyl, --C(.dbd.O)Het, where Het represents a nitrogen-containing heterocyclic group, or one or more halogen atoms or R.sup.1 represents C.sub.3-6 cycloalkyl optionally substituted by C.sub.1-4 alkyl and R.sup.2 represents H or R.sup.1, or R.sup.1 represents C.sub.1-4 alkylthio and R.sup.2 represents H, or A represents R.sup.p (R.sup.q)--C.dbd.N-- (wherein R.sup.p represents C.sub.1-4 alkoxy or amino substituted by one or two C.sub.1-4 alkyl groups and R.sup.q represents H or C.sub.1-4 alkyl) or A represents 2-oxo-azetidin-1-yl, 2-oxo-pyrrolidin-1-yl or 2-oxo-piperidin-1-yl optionally substituted by C.sub.
    Type: Grant
    Filed: July 13, 1983
    Date of Patent: December 16, 1986
    Assignee: May & Baker Limited
    Inventors: Leslie R. Hatton, Edgar W. Parnell, David A. Roberts