Recent advances in azasteroids chemistry

Singh, 1970, Azasteroids: syntheses and significance, Indian J Pharm Educ, 4, 2 Akhrem, 1982, Complete synthesis, structure, and function of 8-azasteroids—a new class of biologically active compounds. Vestsi Akademii Navuk BSSR, Seryya Khimichnykh Navuk, 6, 81 Ninomiya, 1972, Azasteroids. Their syntheses and biological activities, Yuki Gosei Kagaku Kyokaishi, 30, 318, 10.5059/yukigoseikyokaishi.30.318 Morzycki, 1995, Partial synthesis of azasteroid, Polish J Chem, 69, 321 Huisman, 1971, Approaches to total synthesis of heterocyclic steroidal systems, Angew Chem, Int Ed Engl, 10, 450, 10.1002/anie.197104501 Huisman, 1976, Synthesis of heterocyclic steroidal systems, Int Rev Sci: Org Chem, Ser Two, 8, 207 Huisman, 1973, Total synthesis of heterocyclic steroidal systems, Int Rev Sci: Org Chem, Ser One, 8, 235 Morgan, 1963, A novel synthesis of aromatic aza steroids, Chem Industry, 293 Anderson, 1968, Selective retention of dihydrotestosterone by prostatic nuclei, Nature, 219, 277, 10.1038/219277a0 Oumzil, 2005, First total synthesis of N-oxido-3-aza-1,3,5(10)-trieno steroids, Synlett, 11, 1695 Mariet, 2002, First [2+2]-cycloaddition of a 3,4-didehydropyridine and a ketene dialkyl acetal, Tetrahedron Lett, 43, 5789, 10.1016/S0040-4039(02)01176-0 Oppolzer, 1971, Thermal rearrangement of N-(l-benzocyclobutenyl)vinylacetamide. Kinetics and mechanism, J Am Chem Soc, 93, 3834, 10.1021/ja00744a084 Oppolzer, 1971, Intramolecular cycloadditions of o-quinodimethanes, J Am Chem Soc, 93, 3833, 10.1021/ja00744a083 Kametani, 1976, A formal regio- and stereoselective total synthesis of estrone. A convenient synthesis of D-homoestrone, J Am Chem Soc, 98, 3378, 10.1021/ja00427a057 Kametani, 1977, A stereoselective total synthesis of estrone by an intramolecular cycloaddition reaction of olefinic o-quinodimethane, J Am Chem Soc, 99, 3461, 10.1021/ja00452a045 Oppolzer, 1977, New synthetic methods. Intramolecular [4+2]- and [3+2]-cycloadditions in organic synthesis, Angew Chem, 89, 10, 10.1002/ange.19770890105 Oppolzer, 1978, Intramolecular cycloaddition reactions of o-quinodimethans in organic synthesis, Synthesis, 793, 10.1055/s-1978-24895 Kametani, 1981, Recent advances in the total synthesis of steroids via intramolecular cycloaddition reactions, Tetrahedron, 37, 3, 10.1016/S0040-4020(01)97707-5 Nemoto, 1998, Second generation of steroid synthesis via o-quinodimethane, Tetrahedron, 54, 5425, 10.1016/S0040-4020(98)00017-9 Pellissier, 1995, Preparation of tertiary alcohols and y-lactones from allylsilanes and anhydrides, Bull Soc Chim France, 132, 637 Krapcho, 1982, Synthetic applications of dealkoxycarbonylations of malonate esters, β-keto esters, α-cyano esters and related compounds in dipolar aprotic media, Synthesis, 11, 893, 10.1055/s-1982-29991 Iwama, 1998, Pummerer reaction of 2-vinylcyclopropyl sulfoxides: generation and reactions of butadienylthionium ion intermediates, J Chem Soc, Perkin Trans 1: Org Bio-Org Chem, 9, 1569, 10.1039/a708724a Tsuji, 1976, Convenient general synthetic method for 1,4-and 1,5-diketones by palladium catalyzed oxidation of α-allyl and α-3-butenyl ketones, Tetrahedron Lett, 34, 2975, 10.1016/S0040-4039(01)85504-0 Miller, 1990, Improved method for the Wacker oxidation of cyclic and internal olefins, J Org Chem, 55, 2924, 10.1021/jo00296a067 Pellissier, 1997, Regiochemistry of Wacker-type oxidation of vinyl group in the presence of neighboring oxygen functions, Tetrahedron, 53, 7577, 10.1016/S0040-4020(97)00449-3 Oumzil, 2006, First total synthesis of (±)-3-aza-11-oxa- l,3,5(10)-trieno steroids, Steroids, 71, 886, 10.1016/j.steroids.2006.06.003 Cachoux, 2000, First total synthesis of 11-thia steroids, Synlett, 418 Oumzil, 2005, First total synthesis of 3-aza-11-thia- l,3,5(10)-trieno steroids, Tetrahedron Lett, 46, 5799, 10.1016/j.tetlet.2005.06.150 Yelm, 1999, A simple method for in situ generation of thiols from thioacetates, Tetrahedron Lett, 40, 1101, 10.1016/S0040-4039(98)02591-X Gupta, 1996, Synthesis and biological activity of azasteroidal [3,2-c]- and [17,16-c]pyrazoles, Eur J Med Chem, 31, 241, 10.1016/0223-5234(96)89140-9 Bolt, 1938, Preparation of sterol derivatives with nuclear substituted nitrogen, Recueil des Travaux Chimiques des Pays-Bas et de la Belgique, 57, 905, 10.1002/recl.19380570819 Edward, 1961, Oxidation of cholest-4-en-3-one with periodate-permanganate, Can J Chem, 39, 599, 10.1139/v61-072 Singh, 1974, Vilsmeier–Haack reaction with steroid lactams, Indian J Chem, 12, 1210 Ranju, 1994, Vilsmeier–Haack reaction of azasteroids, Indian J Chem, 33B, 269 Bowden, 1946, Acetylenic compounds. Preparation of acetylenic ketones by oxidation of acetylenic carbinols and glycols, J Am Chem Soc, 39, 10.1039/jr9460000039 Hasserodt, 2000, A class of 4-aza-lithocholic acid-derived haptens for the generation of catalytic antibodies with steroid synthase capabilities, Bioorg Med Chem, 8, 995, 10.1016/S0968-0896(00)00036-5 Li, 1995, Synthesis and in vitro activity of 17 beta-(N-alkyl/arylformamido)- and 17 beta-[(N-alkyl/aryl)alkyl/arylamido]-4-methyl-4-aza-3-oxo-5 alpha-androstan-3-ones as inhibitors of human 5 alpha-reductases and antagonists of the androgen receptor, J Med Chem, 38, 1158, 10.1021/jm00007a013 Demir, 1987, Synthesis of biological markers in fossil fuels. A synthesis of 5α-cholan-24-oic acid, Org Prep Proc Int, 19, 197, 10.1080/00304948709356187 Rasmusson, 1986, Azasteroids: structure–activity relationships for inhibition of 5 alpha-reductase and of androgen receptor binding, J Med Chem, 29, 2298, 10.1021/jm00161a028 Piniella, 1987, Photochemical reactions. Sensitized photooxygenation of N-methylated 4-aza-5-androsten-3-one and 4-aza-5-androstene steroidal systems, Bull Chem Soc Jpn, 60, 3011, 10.1246/bcsj.60.3011 Singh, 1973, Steroids and related studies. 4-Azaspirostan analogs and related studies, Indian J Chem, 11, 1254 Corey, 1979, Studies on the total synthesis of rifamycin. A method for the stereo specific synthesis of the carbonyl-conjugated 1,3-diene unit [C(15) to C(20)], Tetrahedron Lett, 2317, 10.1016/S0040-4039(01)93961-9 Borch, 1972, An asymmetric synthesis of alcohols, amines, and amino acids, J Org Chem, 37, 2347, 10.1021/jo00979a032 Gomez-Parra, 1985, Carbamates from secondary amines and alkyl chlorides under phase-transfer conditions, Synthesis, 3, 282, 10.1055/s-1985-31178 Yadav, 2004, Synthesis of 3-oxo-4-aza-5β- system from (25R)-3-oxo-A-norspirostane, Asian J Chem, 16, 1027 Singh, 1966, Synthesis o 4,5-epoxy-22β-spirostan-3-one and its derivatives, Indian J Chem, 4, 377 Rahier, 1996, Sterol biosynthesis: strong inhibition of maize Δ5,7-sterol Δ7-reductase by novel 6-aza-B-homosteroids and other analogs of a presumptive carbocationic intermediate of the reduction reaction, Biochemistry, 35, 7069, 10.1021/bi9528154 Fang, 1996, Synthesis of 6-azaandrostenones, PCT Int Appl, 48 Lazbin, 1986, Direct conversion of aliphatic carboxamides to alkylammonium tosylates with [hydroxy(tosyloxy)iodo]benzene, J Org Chem, 51, 2669, 10.1021/jo00364a010 Aster, 1997, 16-Substituted-6-az-steroid 5-alpha-reductase inhibitors, PCT Int Appl, 46 Fetizon, 1967, Synthesis of 2-oxo steroids, Comptes Rendus des Seances de l’Academie des Sciences, Serie C: Sciences Chimiques, 265, 929 Xie, 2001, Structure–activity relationship of aza-steroids as PI-PLC inhibitors, Bioorg Med Chem, 9, 1073, 10.1016/S0968-0896(00)00302-3 Knof, 1963, Azasteroids IV. 6-Azasteroids, Annalen, 670, 88, 10.1002/jlac.19636700114 Kasal, 2005, Neurosteroid analogues: synthesis of 6-aza-allopregnanolone, Tetrahedron, 61, 2269, 10.1016/j.tet.2005.01.055 Kasal, 1999, On steroids. CDIII. Epalons: synthesis of 7-norallopregnanolone. Collection of Czechoslovak, Chem Commun, 64, 1471 Campos Neves, 1999, Improved syntheses of aromatase inhibitors and neuroactive steroids. Efficient oxidations and reductions at key positions for bioactivity, Tetrahedron, 55, 3255, 10.1016/S0040-4020(98)01138-7 Rao, 2004, Review on the synthesis of 8-azasteroids, Curr Org Chem, 8, 1521, 10.2174/1385272043369881 Back, 1995, A convenient synthesis of 11-aza-C-homoestranes, Synthesis, 162, 10.1055/s-1995-3887 Collins, 1983, The structure and function of estrogens. IV. Synthesis of 17α-ethynylestradiol specifically polydeuterated in ring C, Aust J Chem, 36, 339, 10.1071/CH9830339 Cambie, 1970, Aromatic steroids. IV. Chromium trioxide oxidation of some oestra-l,3,5(10),9(ll)-tetraenes, J Chem Soc (C), 1706 Cambie, 1968, Aromatic steroids. I. Oxidation products of 3-methoxyestra-l,3,5(10)-trien-17-beta-yl acetate, J Chem Soc (C), 2603 Cachoux, 2001, A new efficient synthesis of 11-aza steroids, Tetrahedron Lett, 42, 843, 10.1016/S0040-4039(00)02118-3 Cachoux, 2002, Total synthesis of 11-azasteroids, Synth Commun, 32, 3549, 10.1081/SCC-120014965 Stevens, 1982, An efficient and remarkably regioselective synthesis of benzocyclobutenones from benzynes and 1,1-dimethoxyethylene, J Org Chem, 47, 2393, 10.1021/jo00133a031 Overman, 1978, trans-l-N-Acylamino-1,3-dienes: preparation from dienoic acids, J Org Chem, 43, 2164, 10.1021/jo00405a017 Romero, 1996, Synthesis of an azasteroid using acyl iminium ion-initiated tandem cyclization, J Org Chem, 61, 6974, 10.1021/jo960673t Ninomiya, 1974, Phosphorus in organic synthesis. Diphenyl phosphorazidate (DPPA). A new convenient reagent for a modified Curtius reaction, Tetrahedron, 30, 2151, 10.1016/S0040-4020(01)97352-1 Sinhababu, 1987, tert-Butyldimethylsilyl ethers of phenols: their one step conversion to benzyl or methyl ethers and utility in regioselective ortho-lithiation, Tetrahedron Lett, 4139, 10.1016/S0040-4039(00)95560-6 Speckamp, 1985, Intramolecular reactions of N-acyliminium intermediates, Tetrahedron, 41, 4367, 10.1016/S0040-4020(01)82334-6 Lopez-Call, 1996, Synthetic applications of conjugated nitrones. A novel entry to the 13-azasteroid system, Liebigs Ann, 1855, 10.1002/jlac.199619961120 Gilchrist, 1988, Synthesis of chrysenes and other a-fused phenanthrenes by a palladium(0) coupling-electrocyclic ring closure sequence, J Chem Soc, Perkin Trans 1, 2595, 10.1039/P19880002595 Sonogashira, 1975, Convenient synthesis of acetylenes. Catalytic substitutions of acetylenic hydrogen with bromo alkenes, iodo arenes, and bromopyridines, Tetrahedron Lett, 4467, 10.1016/S0040-4039(00)91094-3 Hamada, 1987, New methods and reagents in organic synthesis. 67. A general synthesis of derivatives of optically pure 2-(l-aminoalkyl)thiazole-4-carboxylic acids, J Org Chem, 52, 1252, 10.1021/jo00383a014 Sultani, 2005, Azasteroids. Synthesis by Diels–Alder Reaction between maleimides, citraconimide, and triazolindiones and 1-(1-trialkylsiloxyvinyl)-3,4-dihydronaphthalene derivatives, Monatshefte fuer Chemie, 136, 1651, 10.1007/s00706-005-0344-5 Hajos, 1964, Stereochemical studies of octahydrophenanthrenes, J Org Chem, 29, 2527, 10.1021/jo01032a011 Salley, 1982, Studies on simplified ergoline derivatives. A general six-step synthesis of phenyl-substituted 4-methyl-3,4,4a,5,6,10b-hexahydro-benzo[f]quinolin-l(2H)-one analogs, J Heterocyclic Chem, 19, 545, 10.1002/jhet.5570190319 Paquette, 1980, Silanes in organic synthesis. 8. Preparation of vinylsilanes from ketones and their regiospecific cyclopentenone annulation, J Org Chem, 45, 3017, 10.1021/jo01303a020 Ireland, 1979, Stereochemistry of the Diels–Alder reaction of vinylcyclohexene or l-[α-(tert-butyldimethylsilyloxy)vinyl]-Δ1-cyclohexene and 2-methylcyclopentenone, J Org Chem, 44, 3583, 10.1021/jo01334a032 Jiang, 2001, Synthesis of (5α)-17-azaandrostan-3-ols and (5α)-17-aza-D-homoandrostan-3-ols and their N-acylated derivatives, Steroids, 66, 655, 10.1016/S0039-128X(01)00095-2 Huffman, 1954, 16-Substituted steroids. IX. Androstan-3β-ol-6-one, J Biol Chem, 207, 431, 10.1016/S0021-9258(18)71284-2 Hassner, 1962, The cleavage reaction of 16-oximino-17-keto steroids, J Org Chem, 27, 1760, 10.1021/jo01052a065 Wallis, 1946, The Hofmann reaction, vol. 3, 267 Radlick, 1974, A versatile modification of the Hofmann rearrangement, Synthesis, 290, 10.1055/s-1974-23298 Wang, 2003, Preparation of (5α, 13α)-D-azasteroids as key precursors of a new family of potential GABAA receptor modulators, Steroids, 68, 677, 10.1016/S0039-128X(03)00099-0 Huffman, 1954, 16-Substituted steroids. IX. Androstan-3β-ol-16-one, J Biol Chem, 207, 431, 10.1016/S0021-9258(18)71284-2 Jones, 1969, Studies in the steroid group. Part LXXIX. Preparation of 2-aza-3-oxo, 3-aza-2-oxo-, 16-aza-17-oxo- and 17-aza-16-oxo-5α-androstane, and of 3-aza-2-oxo-5α-cholestane, J Chem Soc (C), 1597 Eberbach, 1992, The synthesis of isoannulated pyrroles and α-pyridones, Tetrahedron Lett, 33, 61, 10.1016/S0040-4039(00)77673-8 Eberbach, 1989, Heterocyclic synthesis by electrocyclization of extended dipoles: α novel access to the indolizine and quinolizine systems, Tetrahedron Lett, 30, 5591, 10.1016/S0040-4039(01)93807-9 Eberbach, 1987, Pyrrole and pyridine derivatives via 1,7-cyclization of butenynyl nitrones. The product-determining influence of substituents on the deactivation pathway of the oxazacycloallene intermediates, Tetrahedron Lett, 28, 2689, 10.1016/S0040-4039(00)96182-3 Berg-Nielsen, 1975, Evidence for an ionic mechanism for the reaction of 2-cyclopropylpyridine N-oxide with acetic anhydride., Acta Chem Scand, Ser B, 32, 985, 10.3891/acta.chem.scand.29b-0985 Reimann, 1976, Intramolecular alkylations of aromatic compounds, IV. Synthesis and reduction of N-methyl-5,6,7,8-tetrahydroquinaldinium iodide, Liebigs Ann Chem, 610, 10.1002/jlac.197619760404 Aulenta, 2006, Heck reaction of quinoline-derived nonaflates, Synlett, 18, 2993 Martinez, 1984, Hydrogenative cleavage of phenolic and enolic perfluroalkanesulfonates, Synthesis, 481 Dinesh, 1999, A new samarium diiodide induced reaction: intramolecular attack of ketyl radical anions on aryl substituents with formation of 1,4-cyclohexadiene derivatives, Angew Chem, Int Ed, 38, 789, 10.1002/(SICI)1521-3773(19990315)38:6<789::AID-ANIE789>3.0.CO;2-W Nandanan, 2000, Competition between novel 8-endo-dig and 6-trig cyclizations of samarium ketyls leading either to benzannulated cyclooctene or to hexahydronaphthalene derivatives, Tetrahedron, 56, 4267, 10.1016/S0040-4020(00)00353-7 Berndt, 2001, Substituent effects in samarium diiodide-induced 6-trig cyclizations of γ-aryl ketones to functionalized hexahydronaphthalene derivatives, Synlett, 1290, 10.1055/s-2001-16051 Gross, 2002, Samarium diiodide-induced diastereoselective synthesis of hexahydroquinoline derivatives, Synlett, 2027 Berndt, 2003, Novel stereoselective synthesis of highly functionalized benzannulated pyrrolizidines and indolizidines by samarium diiodide induced cyclizations of indole derivatives, Org Lett, 5, 4305, 10.1021/ol0355581 Berndt, 2004, Stereoselective formation of tri- and tetracycles by samarium diiodide-induced cyclizations of naphyl-substituted ketones, Org Lett, 6, 957, 10.1021/ol036456d Berndt, 2004, New samarium diiodide-induced ketyl couplings—from analogous reactions to serendipitously discovered processes, Synlett, 422 Sasaki, 1995, Polycyclic N-heterocyclic compounds. Synthesis and evaluation of anti-platelet aggregation activity of 11,13,15-triazasteroid and related compounds, Heterocycles, 41, 2251, 10.3987/COM-95-7163 Boatman, 1965, Alkylations at the α′-methylene or methinyl group of α-formyl cyclic ketones through their dicarbanions. Angular alkylations, J Am Chem Soc, 87, 82, 10.1021/ja01079a015 Johnson, 1945, Plan for distinguishing between some five- and six-membered ring ketones, J Am Chem Soc, 67, 1745, 10.1021/ja01226a038 Jindal, 1996, Synthesis of some novel heterocyclic steroids by Beckmann rearrangement, Indian J Chem, 35B, 775 Jindal, 1991, Synthesis and anti-inflammatory activity of 2′-phenyl steroidal[17,16-c]pyrazoles, Eur J Med Chem, 26, 651, 10.1016/0223-5234(91)90201-W Eastham, 1995, 35 Camerino, 1956, Synthesis and anabolic activity of 4-substituted testosterone analogs. Synthesis and anabolic activity of 4-substituted testosterone analogs, J Am Chem Soc, 78, 3540, 10.1021/ja01595a076 Covey, 2000, Neurosteroid analogues. Structure–activity studies of N-acylated 17α-aza-D-homosteroid analogues of the anesthetic steroids (3α,5α)- and (3α,5/β)-3-hydroxypregnan-20-one, J Med Chem, 43, 3201, 10.1021/jm0002477 Revelli, 1993, Synthesis of 17a-alkyl and 17a-aryl-3β-acetoxy- and 3β-methoxy-17α-aza-D-homoandrost-5-en-17-one, Steroids, 58, 181, 10.1016/0039-128X(93)90066-V Stojanovic, 2001, Synthesis and chemical behaviour of 17α-butyl-3β, 17β-dihydroxy-16-oximino-5-androstene, J Serb Chem Soc, 66, 23, 10.2298/JSC0101023S Petrovic, 2004, Synthesis of some D-homo-D-aza-estratrien derivatives, Acta Periodica Technologica, 35, 225, 10.2298/APT0435225P Miljkovic, 1977, Beckmann fragmentation reaction of 3-methoxy-17β-hydroxyestra-1,3,5(10)-trien-16-one oxime, J Org Chem, 42, 2101, 10.1021/jo00432a015 Hassner, 1963, Cleavage vs Beckmann rearrangement in a-oximino ketones, J Org Chem, 28, 304, 10.1021/jo01037a006 Gupta, 1999, Synthesis and biological activity of some D-ring modified estrone derivatives, Indian J Chem, 38B, 563 Pejanovic, 1999, 17-Acetals of 3-methoxy-17-oxo-16,17-secoestra-l,3,5(10)-trien-16-nitrile, Proc Nat Sci Matica Srpska Novi Sad, 97, 5 Magyar, 2003, Synthesis of N-[2-(2-pyridyl)ethyl]-17α-aza-D-homosteroids and their biomimetic copper-mediated ligand hydroxylations with molecular oxygen, Tetrahedron Asymmetry, 14, 1925, 10.1016/S0957-4166(03)00362-8 Kaufmann, 1951, Steroids. XVI. Beckmann rearrangement of 17-keto steroid oximes, J Am Chem Soc, 73, 1779, 10.1021/ja01148a103 Carman, 1965, Structure and partial synthesis of canaric acid, Aust J Chem, 18, 213, 10.1071/CH9650213 Robinson, 1965, Photolysis of 3,5-alpha-cyclo-6-ketosteroids, Tetrahedron, 21, 743, 10.1016/0040-4020(65)80007-2 Borch, 1968, New method for the reduction of secondary and tertiary amides, Tetrahedron Lett, 9, 61, 10.1016/S0040-4039(01)98727-1 Koutsourea, 2003, Synthetic approaches for the synthesis of a cytostatic steroidal B-D bilactam, Steroids, 68, 659, 10.1016/S0039-128X(03)00095-3 Singh, 1977, Steroids and related studies. Part XXXVI. 7α-17α-Diaza-7,17-dioxo-B,D-dihomo-5-androsten-3β-yl acetate, Indian J Chem, 15B, 101 Salvador, 1997, Copper-catalyzed allylic oxidation of Δ5-steroids by t-butyl hydroperoxide, Tetrahedron Lett, 38, 119, 10.1016/S0040-4039(96)02231-9 Pouzar, 1998, Synthesis of (19E)-3β,7α-dihydroxy-17-oxoandrost-5-en-19-al-19-(O-carboxymethyl)oxime, a new hapten for 7α-hydroxydehydroepiandro sterone (3(3,7 a-dihydroxy-andro st-5-en-17-one), Steroids, 63, 454, 10.1016/S0039-128X(98)00047-6 Salmond, 1978, Allylic oxidation with 3,5-dimethylpyrazole chromium trioxide complex. Steroidal Δ5-7-ketones, J Org Chem, 43, 2057, 10.1021/jo00404a049 Singh, 1969, Steroids. Part X. Some 5-en-7-ones and 7α-aza-B-homo-5-en-7-ones in spirostan, androstan and pregnane series, Indian J Chem, 7, 1084 Gawley, 1988, The Beckmann reactions: rearrangements, elimination–additions, fragmentations and rearrangement–cyclizations, Org React, 35, 1 Frank, 2005, Synthesis of some novel D-dihomo-aza- and D-dihomo-oxa-steroid derivatives in the estrone series, Synlett, 18, 2814 Guzzi, 1977, Cleavage of the D ring in 16-substituted steroids, Gazz Chimltal, 107, 75 Schneider, 1983, A convenient method for the formation of 16-methylene-17-keto steroids, Synthesis, 665, 10.1055/s-1983-30466 Trehan, 1995, A highly stereoselective synthesis of des-AB-aromatic azasteroids, Indian J Chem, 34B, 484 Kametani, 1978, Asymmetric total synthesis of estradiol by an intramolecular cycloaddition of benzocyclobutene derivative, J Am Chem Soc, 100, 36218, 10.1021/ja00487a044 Akhrem, 1985, Search for selective heterosteroid-type immunotropic substances., Khimiya i Biol Immunoregulyatorov, Riga, 265 Anderson, 1968, Selective retention of dihydrotestosterone by prostatic nuclei, Nature, 219, 277, 10.1038/219277a0 Voigt, 1970, Transformation of testosterone into 170-hydroxy-5α-androstan-3-boyne microsomal preparations of human skin, J Biol Chem, 245, 5594, 10.1016/S0021-9258(18)62696-1 Labrie, 1993, Combination therapy for prostate cancer, Cancer, 71, 1059, 10.1002/1097-0142(19930201)71:3+<1059::AID-CNCR2820711426>3.0.CO;2-6 Kirby, 1991, The potential value of 5α-reductase inhibition in the treatment of bladder outflow obstruction due to benign prostatic hyperplasia, World J Urol, 9, 41, 10.1007/BF00184713 Sansone, 1971, Differential rates of conversion of testosterone to dihydrotestosterone in acne and normal human skin—a possible pathogenic factor in acne, J Invest Dermatol, 56, 366, 10.1111/1523-1747.ep12261252 Serafini, 1986, Increased 5a-reductase activity in idiopathic hirsutism, Fertil Steril, 43, 74, 10.1016/S0015-0282(16)48320-2 Diani, 1992, Hair growth effects of oral administration of finasteride, a steroid 5a-reductase inhibitor alone and in combination with topical minoxidil in the balding stumptail macaque, J Clin Endocrinol Metab, 74, 45, 10.1210/jc.74.2.345 Labrie, 1992, Structure of human type II 5a-reductase gene, Endocrinology, 131, 1571, 10.1210/en.131.3.1571 Singh, 1991, Heterosteroids and drug research, Prog Med Chem, 28, 233, 10.1016/S0079-6468(08)70366-7 Lourdusamy, 1997, Synthesis and in vitro study of 17β-[N-ureylene-N,N′-disubstituted]-4-methyl-4-aza-5α-androstan-3-ones as selective inhibitors of type I 5α-reductase, Bioorg Med Chem, 5, 305, 10.1016/S0968-0896(96)00241-6 Strachan, 1964, Synthesis of 2′-(2,4-dieno[3,2-c]pyrazole, J Med Chem, 7, 355, 10.1021/jm00333a024 Hirschmann, 1964, Synthesis of pregn-4-eno[3,2-c]pyrazoles related to 9-alpha-fluoro-16-alpha-methylcortisol, J Med Chem, 7, 352, 10.1021/jm00333a023 Piomelli, 1996 Laychock, 1999 Xie, 2000, 3β-Hydroxy-6-aza-cholestane and related analogues as phosphatidylinositol specific phospholipase C (PI-PLC) inhibitors with antitumor activity, Bioorg Med Chem, 8, 699, 10.1016/S0968-0896(00)00014-6 Phillipps, 1975, Structure–activity relations in steroidal anesthetics, J Steroid Biochem, 6, 607, 10.1016/0022-4731(75)90041-2 Lambert, 1995, Neurosteroids and GABAA receptor function, Trends Pharmacol Sci, 16, 295, 10.1016/S0165-6147(00)89058-6