1. A method of fabricating an operating arm for a construction machine, said operating arm being constituted by a plural number of joined plates and in the shape of a square tubular structure in cross section, said method comprising the steps of:
preparing a wide plate-like material having alternately thick and thin wall portions in a transverse direction by butt welding side to side said plural number of joined plates in different thicknesses;
bending said wide plate-like material along said thick wall portions to form thick wall corner portions of said square tubular structure, and to form a U-shaped structure having a U-shape in cross section with an opening on one side, through plastic deformation; and
welding a separate plate-like member to said U-shaped structure to close said opening to form said square tubular structure.
2. The method of fabricating an operating arm for a construction machine as defined in claim 1, wherein said preparing step further comprises welding a boss mounting thick plate to be formed into a boss mount member to one longitudinal end of said wide plate-like material, and bending said boss mounting thick plate into a U-shape in cross section simultaneously with the bending of said wide plate-like material to form said U-shaped structure.
3. The method of fabricating an operating arm for a construction machine as defined in claim 1, wherein said thin and thick plates are joined by high energy density welding of deep penetration in said preparing step.
4. The method of fabricating an operating arm for a construction machine according to claim 1, wherein said preparing step includes positioning surfaces of said thin wall portion flush with surfaces of said thick wall portions on an outside in the direction of thickness but indented from said thick wall portions on an inside in the direction of thickness prior to butt welding.
5. The method of fabricating an operating arm for a construction machine according to claim 1, wherein said preparing step includes positioning surfaces of said thin wall portions indented from surfaces of said thick wall portions on an outside in the direction of thickness but flush with said thick wall portions on an inside in the direction of thickness prior to butt welding.
6. The method of fabricating an operating arm for a construction machine according to claim 1, wherein said preparing step includes positioning surfaces of said thin wall portions indented from surfaces of said thick wall portions on both sides in the direction of thickness prior to butt welding.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for preparation of a 17\u03b1-alkynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol essentially free of steroid side-product lacking an oxygen substituent at position 7 comprising the steps of
(a) Contacting a suitably protected dehydroepiandrosterone with an oxidizing agent to directly introduce the \u2550O (ketone) functional group at position 7;
(b) Contacting a suitably protected androst-5-en-7,17-dione-3\u03b2-ol with a reducing agent to convert the \u2550O (ketone) functional group at position 7 to hydroxyl predominately in the \u03b2-configuration; and
(c) Contacting an optionally protected alkynyl anion with suitably protected androst-5-en-17-one-3\u03b2,7\u03b2-diol to introduce an alkynyl substituent at position 17 predominately in the \u03b1-configuration by addition of the alkynyl anion to the \u2550O (ketone) functional group at position 17.
2. The process of claim 1 wherein the 17\u03b1-alkynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol is 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol.
3. The process of claim 1 wherein the suitably protected dehydroepiandrosterone has the structure of
wherein R1 is \u2014H, C1-6 alkyl, C3-6 cycloalkyl, optionally substituted aryl or optionally substituted heteroaryl.
4. The process of claim 1 wherein the suitably protected androst-5-en-7,17-dione-3\u03b2-ol has the structure of
5. The process of claim 1 wherein the suitably protected androst-5-en-7,17-dione-3\u03b2-ol has the structure of
wherein R1 is \u2014H, C1-6 alkyl, C3-6 cycloalkyl, optionally substituted aryl or optionally substituted heteroaryl and R2 is \u2014H, C1-6 alkyl or aryl.
6. The process of claim 5 wherein R1 is C1-6 alkyl or phenyl.
7. The process of claim 1 wherein the suitably protected androst-5-en-17-one-3\u03b2,7\u03b2-diol has the structure of
wherein each R3 and each R4 independently are C1-6 alkyl or aryl.
8. The process of claim 7 wherein the alkynyl anion has the structure of M-C\u2261C\u2014Si(R5)3 wherein R5 independently are C1-6 alkyl or aryl and M is a Group I, Group II or transition metal.
9. The process of claim 8 wherein M is Li, Mg or Zn.
10. The process of any one of claims 1-9 wherein R1, R2, R3, and R4 are \u2014CH3.
11. A process for preparation of 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol essentially free of 17\u03b1-ethynyl-androst-5-ene-3\u03b2,17\u03b2-diol comprising the steps of
(a) Contacting suitably protected androst-5-en-7,17-dione-3\u03b2-ol having the structure of
with a reducing agent to convert the \u2550O (ketone) functional group at position 7 to hydroxy predominately in the \u03b2-configuration;
(b) Converting the ketal functional group at position 17 in the product from step (a) to the \u2550O (ketone) functional group; and
(c) converting the acetoxy group at position 3 to 3\u03b2-hydroxy
or
(b\u2032) converting the acetoxy group at position 3 in the product from step (a) to 3\u03b2-hydroxy; and
(c\u2032) converting the ketal group at position 17 to the \u2550O (ketone) functional group;
and
(d) Converting the hydroxyl groups at positions 3\u03b2 and 7\u03b2 in the product from steps (b) and (c) or steps (b\u2032) and (c\u2032) having the structure of
to Me3SiO\u2014 groups; and
(e) Contacting the product from step (e) with lithium trimethylsilyl-acetylide to introduce an ethynyl substituent at position 17 predominately in the \u03b1-configuration by addition of the acetylide to the \u2550O (ketone) functional group at position 17;
(f) Contacting the reaction product from step (e) having the structure of
with an aqueous acid to replace \u2014SiMe3 with \u2014H,
whereby 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol is obtained essentially free of 17\u03b1-ethynyl-androst-5-ene-3\u03b2,17\u03b2-diol.
12. A process for preparation of 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol essentially free of 17\u03b1-ethynyl-androst-5-ene-3\u03b2,17\u03b2-diol comprising the steps of
(a) Contacting a suitably protected androst-5-en-7,17-dione having the structure
with a reducing agent to convert the \u2550O (ketone) functional group at position 7 to hydroxy predominately in the \u03b2-configuration;
(b) Converting the oxime at position 17 in the reaction product from step (a) to the \u2550O (ketone) functional group;
(c) Converting the acyloxy group in the reaction product from step (b) to 3\u03b2-hydroxy;
(d) Converting the hydroxy groups at positions 3 and 7 in the product from step (c) to Me3SiO\u2014 groups; and
(e) Contacting the reaction product from step (d) with lithium trimethylsilyl-acetylide to introduce an ethynyl substituent at position 17 predominately in the \u03b1-configuration by addition of the acetylide to the \u2550O (ketone) functional group at position 17,
whereby 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol is obtained essentially free of 17\u03b1-ethynyl-androst-5-ene-3\u03b2,17\u03b2-diol.
13. The process of claim 1, 11 or 12 comprising the additional step of purifying 17\u03b1-alkynyl-androst-5-ene-3\u03b2,7\u03b2, 17\u03b2-triol product by recrystallization.
14. The process of claim 14 wherein the 17\u03b1-alkynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol product is purified by recrystallization from methanol-water.
15. The process of claim 14 wherein the 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol is 17\u03b1-ethynyl-androst-5-ene-3\u03b2,7\u03b2,17\u03b2-triol.