(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date WO 2012/140576 Al 18 October 2012 (18.10.2012) P O P C T (51) International Patent Classification: (81) Designated States (unless otherwise indicated, for every C07H 5/06 (2006.01) C07H 15/18 (2006.01) kind of national protection available): AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, (21) International Application Number: CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO, PCT/IB2012/05 1759 DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, (22) International Filing Date: HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, KR, 11 April 2012 ( 11.04.2012) KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, (25) Filing Language: English OM, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SC, SD, (26) Publication Language: English SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (30) Priority Data: 1106095. 1 11 April 201 1 ( 11.04.201 1) GB (84) Designated States (unless otherwise indicated, for every kind of regional protection available): ARIPO (BW, GH, (71) Applicant (for all designated States except US): GLY- GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, SZ, TZ, COM A S [DK/DK]; Diplomvej 373, 2800 Kgs. Lyngby UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, (DK). TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, (72) Inventors; and LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, (75) Inventors/Applicants (for US only): VRASD3AS, Ioannis SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, [GR/GR]; Papapetrou 17, 5513 1 Thessaloniki (GR). GW, ML, MR, NE, SN, TD, TG). DEKANY, Gyula [HU/AU]; 46 Furness Crescent, Sinna- mon Park, QLD 4073 (AU). JANOSI, Agnes [HU/HU]; Published: Regenyes u. 5, 1221 Budapest (HU). HEDEROS, Markus — with international search report (Art. 21(3)) [SE/SE]; Byggmastaregatan 103, 23343 Svedala (SE). ROHRIG, Christoph [DE/DE]; Drei-Lerchen 4, 78357 — before the expiration of the time limit for amending the Muhlingen (DE). claims and to be republished in the event of receipt of amendments (Rule 48.2(h)) (74) Agent: SELDEN, Deborah, A.; Beck Greener, Fulwood House, 12 Fulwood Place, London, WC1V 6HR (GB). (54) Title: N-SUBSTITUTED MANNOSAMINE DERIVATIVES, PROCESS FOR THEIR PREPARATION AND THEIR USE (57) Abstract: A compound of the formula (I) wherein R i is a group removable by hydrogenolysis,and wherein R 2 is OH or R 2 is -NHR wherein R is a group removable by hydro geno lysis. The compound can be made from fructose by a Heyns -rearrangement. The compound can be used then to make - free D-mannosamine or its salts, - D-mannosamine building blocks and mannosamine containing oligo- or polysaccharides, - N-acetyl-D-mannosamine and its hydrates and solvates, - neuraminic acid derivatives and, - viral neuraminidase inhibitors. N-SUBSTITUTED MANNOSAMINE DERIVATIVES, PROCESS FOR THEIR PREPARATION AND THEIR USE FIELD OF THE INVENTION The present invention relates to the provision, synthesis and use of novel mannosamine derivatives. BACKGROUND OF THE INVENTION 2-Amino-2-deoxy-D-mannose (D-mannosamine) mainly in its N-acetylated form (ManNAc) can be found as a building unit of some bacterial capsular polysaccharides and lipopolysaccharides. In addition, N-acetyl-D-mannosamine is the biosynthetic precursor of sialic acid, a unique nine-carbon ketoaldonic acid having many major biological roles. One can obtain D-mannosamine or N-acetyl-D-mannosamine by means of chemical or enzymatic transformations. N-Acetyl-D-glucosamine can be converted into N-acetyl-D- mannosamine via 2-epimerization which can be initiated with bases (organic or inorganic bases as well as basic ion exchange resins are suitable) or epimerase enzymes [1-3]. In these methodologies an equilibrium between N-acetyl-D-glucosamine and N-acetyl-D-mannosamine is formed wherein the gluco compound is favoured, thus sophisticated and/or complicated separation techniques are needed to isolate this minor product from the starting material remaining, reagent and/or enzymes and other undesired by-products. The isolation difficulties, the moderate chemical yield and the relative expense of the starting compound all prevent this procedure being scaled-up in a cost-effective way. In classical synthetic methods, cheap and easily available simple monosaccharides can be transformed into the D-mannosamine framework like D-arabinose (stereoselective aminohomologation of D-arabinose chain via thiazole addition to nitrone [4,5], addition of ammonia to D-arabo-tetraacetoxy-l-nitro-1- hexene [6]), D-glucose (nucleophilic displacement of good leaving groups in C-2 with N- nucleophiles [7], stereoselective reduction of 2-gluculose oximes [8,9]) or D-glucal (intermolecular addition of nitrosyl chloride to the double bond [10], azidonitration of the double bond [ 1 1], intramolecular rhodium(II)-catalyzed oxidative cyclization of glucal-3- carbamates [12,13], [3,3]sigmatropic rearrangement of 4-0-trichloroacetimidyl-hex-2- enopyranosides derived from glucal [14]). These chemical pathways always stand in need of extensive use of protecting groups in order to mask functional groups that would be affected by the key transformational step(s), thus they consist of many elementary chemical steps. Such multistep sequences restrict usefulness and are not attractive for large scale developments because of the long technological time and the use of high number of reagents (which in fact, not uncommonly, can be toxic, of low availability and/or expensive) and/or require lengthy or cumbersome isolation/separation procedures. Reaction of a ketose with an amine giving a ketosyl amine and the subsequent rearrangement of the latter into 2-amino-2-deoxy-aldose is known as Heyns-rearrangement [15]. Theoretically both 2-epimers can be formed, nevertheless the formation of one of the epimers is favoured, presumably because of steric factors. In the Heyns-rearrangement of D- fructose with a primary amine the exclusive formation of the corresponding gluco derivative is observed. Particularly, crystalline fructosyl benzyl amine, obtained as an intermediate by reacting D-fructose with benzyl amine, rearranges exclusively to 2-benzylamino-2-deoxy-D- glucose upon treatment with glacial acetic acid in methanol [16]. On the other hand, the formation of N-benzyl-2-benzylamino-2-deoxy -D-glucopyranosylamine was reported in the reaction of D-fructose with benzyl amine (the latter serves as reactant and solvent also) upon heating [17] or in the presence of a catalytic amount of benzyl ammonium chloride or ZnCl2[18,19]. The synthesis of N-alkyl- or N-(substituted alkyl)-mannosamine glycosides is possible in a tandem reduction-reductive alkylation reaction of 2-azido-2-deoxy-mannose derivatives in the presence of an alkanal or substituted alkanal [20]. The biological significance of mannosamine derivatives always provides an incentive for developing new, short and simple synthetic routes towards them that can be easily scaled- up. It is an aim of the present invention to provide such a method. SUMMARY OF THE INVENTION A first aspect of the present invention relates to N-substituted D-mannosamine derivatives of the following formula 1 and their salts 1 wherein Ri is a group removable by hydrogenolysis, and wherein R2 is OH or R2 is -NHR 3 wherein R3 is a group removable by hydrogenolysis. Preferably, each of the Ri and R2 groups removable by hydrogenolysis is a benzyl or naphthylmethyl group optionally substituted with one or more phenyl, alkyl or halogen groups, more preferably a benzyl group. Preferably, the compound has the following formula 1A 1A wherein Ri is a group removable by hydrogenolysis, preferably a benzyl or naphthylmethyl group optionally substituted with one or more groups selected from phenyl, alkyl or halogen, more preferably a benzyl group; or the following formula IB IB wherein Ri and R 3 are each independently a group removable by hydrogenolysis, preferably a benzyl or naphthylmethyl group optionally substituted with one or more groups selected from phenyl, alkyl or halogen, and more preferably a benzyl group. The second and third aspects of this invention relates to processes for the synthesis of N -substituted D-mannosamine derivatives of formula 1. Specifically: The second aspect of the invention relates to N -substituted D-mannosamine derivatives of the following formula 1A 1A wherein Ri is a group removable by hydrogenolysis, are made by a first process comprising the steps of: a) treating D-fructose with Ri- NH2, preferably benzyl amine, to yield a fructosyl amine derivative; b) isolating the fructosyl amine derivative as a crude product by separating excess Ri-NH 2 from it; and c) treating, preferably in methanol, the crude fructosyl amine derivative with acid, preferably glacial acetic acid, to produce a compound of formula 1A by a Heyns-rearrangement. Preferably, the reaction time allowed for the step of treating D-fructose with Ri-NH 2 to yield a fructosyl amine derivative is at most 2 days, and more preferably at most 24 hours. The third aspect of the invention relates to bis-N -substituted D-mannosamine derivatives of the following formula IB IB wherein Ri and R2 are each independently a group removable by hydrogenolysis, are made by a process comprising the step of treating D-fructose with Ri- NH2, preferably benzyl amine, to produce a compound of formula IB by a Heyns- rearrangement. Preferably, D-fructose is treated with both Ri-NH 2 and a benzyl amine salt catalyst for a Heyns-rearrangement.