<PAGE>

                                                                   EXHIBIT 10.6

                            SECOND AMENDMENT TO LEASE

         This Second Amendment to Lease ("SECOND AMENDMENT") is made as of
November 15, 2000, by and between ARE - 100 PHILIPS PARKWAY, LLC, a Delaware
limited liability company ("LANDLORD"), and MEMORY PHARMACEUTICALS CORP., a
Delaware corporation ("TENANT")

                                    RECITALS

         A. Landlord Is the landlord and Tenant is the tenant under a Lease
dated as of June 4, 1999, as amended by letter agreement dated June 16, 1999,
between Landlord and Tenant, and as further amended by that certain First
Amendment to Lease dated as of February 4, 2000, between Landlord and Tenant
(collectively the "LEASE"), under which Tenant leases approximately 32,000
rentable square feet of space in the building commonly known as 100 Philips
Parkway, Montvale, New Jersey. Capitalized terms used herein without definition
shall have the meanings defined for such terms in the Lease.

         B. Landlord and Tenant desire to amend the Lease to expand the Premises
demised under the Lease by adding approximately 20,000 rentable square feet,
excluding the Mechanical Room, as defined below (the "EXPANSION SPACE")
generally located at the northeast end of the first floor of the building.

         C. Landlord and Tenant desire to amend the Lease to, among other
things, add the Expansion Space to the Premises demised under the Lease and to
provide for the improvement of such space.

                                    AGREEMENT

         Now, therefore, the parties hereto agree that the Lease is hereby
amended as follows:

1. PREMISES. Landlord shall lease to Tenant, and Tenant shall lease from
Landlord, the Expansion Space, consisting of approximately 20,000 rentable
square feet in the Building (excluding the Mechanical Room, as defined below)
and depicted on EXHIBIT A, attached hereto and incorporated herein by this
reference. Following such Amendment, Tenant will lease approximately 52,000
rentable square feet in the Building and Tenant's Share shall be 70.27%. The
actual size of the Expansion Space shall be measured at such time as Landlord
and Tenant shall agree, in accordance with the 1996 Standard Method of Measuring
Floor Area in Office Buildings as adopted by the Building Owners and Managers
Association (ANSI/BOMA Z65.1-1996). The Rent payable hereunder, Tenant's Share
and the aggregate Tenant Improvement Allowance shall all be adjusted, if
required, on the basis of such measurement. Tenant shall have the right to use
156 parking spaces at the Project based upon Tenant's total Premises of
approximately 52,000 rentable square feet, subject to adjustment following any
measurement as provided above. Landlord agrees that it shall consider the
overall use of the Building as well as potential transmission of noise and
vibration into the Expansion Space in connection with its review and approval of
any tenant improvement plans for the remaining space in the Building of which
the Expansion Space is a part.

2. COMMENCEMENT AND TERM. The Lease of the Expansion Space shall commence on
November 15, 2000 (the "EXPANSION SPACE COMMENCEMENT DATE"), and shall expire
May 31, 2010 unless sooner terminated pursuant to the Lease; provided, however,
that if more than an average of $20 per rentable square foot of the Tenant
Improvement Allowance for the Expansion Premises is used by Tenant, the Term of
the Lease is hereby automatically extended to expire 10 years after the first
day of the first full month during which Tenant pays Base Rent based upon the
full amount of the Tenant Improvement Allowance so used by Tenant.

                                       1
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3. RENT.

                  (a)      Tenant shall pay Base Rent at the rate of $10.00 per
         rentable square foot of the Expansion Space, which rent shall be
         subject to periodic adjustment when and as provided in the Lease and
         the First Amendment and shall be further subject to adjustment as
         provided in Section 7 hereof. For purposes of the First Amendment, Base
         Rent for the Expansion Space shall be increased to $13 per rentable
         square foot effective as of January 1, 2004.

                  (b)      Notwithstanding the above, no Base Rent shall be due
         with respect to the Expansion Space for a period of one year after the
         Expansion Space Commencement Date.

4. SECURITY DEPOSIT. Tenant shall within 3 business days of the date hereof
deliver to Landlord an additional deposit (the "SECURITY DEPOSIT") in the amount
of $130,000 as security for Tenant's performance under the Lease and this Second
Amendment. Such Security Deposit may be in the form of a Letter of Credit as
provided in the Lease and shall be held and applied as provided in the Lease.

5. UTILITIES. Tenant shall be entitled to use up to 800 amperes of the electric
service available for the portion of the Building which was not leased to Tenant
under the Lease. Any costs associated with the distribution of electric service
to and within the Expansion Space shall be a Tenant Improvement payable out of
the Tenant Improvement Allowance.

6. UTILITY ROOM. Landlord shall have the right to access the mechanical room
shown on Exhibit A located entirely within the Premises (the "MECHANICAL ROOM")
at all times immediately following oral notice to Tenant or any of Tenant's
employees or security personnel. Landlord shall further have the right to
install additional base building equipment in the Mechanical Room in Landlord's
sole discretion.

7. TENANT IMPROVEMENTS. Landlord shall make available to Tenant an allowance for
the Expansion Space (the "TENANT IMPROVEMENT ALLOWANCE") in the amount of $150
per rentable square foot of the Expansion Space, not to exceed an aggregate
Tenant Improvement Allowance of $3,000,000; provided that the Base Rent shall be
adjusted as provided in Section 4(a) of the Lease to the extent that Tenant uses
more than $20 per rentable square foot of the Expansion Premises of the Tenant
Improvement Allowance. Such Tenant Improvements shall be designed and
constructed pursuant to the Work Letter attached hereto as EXHIBIT B. The
Tenant Improvement Allowance may be used by Tenant only in connection with the
design and construction of improvements to the Expansion Space (the"TENANT
IMPROVEMENTS"); provided, however, that no disbursement of the Tenant
Improvement Allowance shall be made after December 31, 2003. Base Rent for the
Expansion Space shall be adjusted as provided in the Lease when and as the
Tenant Improvement Allowance is disbursed. If more than an average of $20 per
rentable square foot of the Expansion Premises is used by Tenant, the Term of
the Lease is hereby automatically extended to expire 10 years after the first
day of the first full month during which Tenant pays Base Rent based upon the
full amount of the Tenant Improvement Allowance so used by Tenant.

8. MISCELLANEOUS.

                  (a)      This Amendment is the entire agreement between the
         parties with respect to the subject matter hereof and supersedes all
         prior and contemporaneous oral and written agreements and discussions
         with respect to the matters addressed herein. This Amendment may be
         amended only by an agreement in writing, signed by the parties hereto.

                  (b)      This Amendment is binding upon and shall inure to the
         benefit of the parties hereto, their respective agents, employees,
         representatives, officers, directors, divisions, subsidiaries,
         affiliates, assigns, heirs, successors in interest and shareholders.

                                       2

<PAGE>

                  (c)      This Amendment may be executed in any number of
         counterparts, each of which shall be deemed an original, but all of
         which when taken together shall constitute one and the same instrument.
         The signature page of any counterpart may be detached therefrom without
         impairing the legal effect of the signature(s) thereon provided such
         signature page is attached to any other counterpart identical thereto
         except having additional signature pages executed by other parties to
         this Amendment attached thereto.

                  (d)      Landlord and Tenant each represent and warrant that
         it has not dealt with any broker, agent or other person (collectively
         "BROKER") in connection with this transaction, and that no Broker
         brought about this transaction. Landlord and Tenant each hereby agree
         to indemnify and hold the other harmless from and against any claims by
         any Broker claiming a commission or other form of compensation by
         virtue of having dealt with Tenant or Landlord, as applicable, with
         regard to this leasing transaction.

                  (e)      Except as amended and/or modified by this Amendment,
         the Lease is hereby ratified and confirmed and all other terms of the
         Lease shall remain in full force and effect, unaltered and unchanged by
         this Amendment. In the event of any conflict between the provisions of
         this Amendment and the provisions of the Lease, the provisions of this
         Amendment shall prevail. Whether or not specifically amended by this
         Amendment, all of the terms and provisions of the Lease are hereby
         amended to the extent necessary to give effect to the purpose and
         intent of this Amendment.

                            [SIGNATURES ON NEXT PAGE]

                                       3

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         IN WITNESS WHEREOF, this Second Amendment to Lease has been duly
executed and delivered by Landlord and Tenant as of the date first above
written.

                              TENANT:

                              MEMORY PHARMACEUTICALS CORP.,
                              a Delaware corporation

                              By:  /s/ Joanne Leonard
                                   --------------------------------
                              Its: Sr VP, CFO

                              LANDLORD:

                              ARE - 100 PHILLIPS PARKWAY, LLC,
                              a Delaware limited liability company

                              By:  ALEXANDRIA REAL ESTATE EQUITIES, L.P., a
                                   Delaware limited partnership, managing member

                                   By: ARE-QRS CORP.,
                                       a Maryland corporation,
                                       general partner

                                       By:  /s/ Michael C. Keley
                                            -----------------------------
                                       Its: Michael C. Keley
                                            Senior Vice President
                                            Real Estate Legal Affairs

                                       4

<PAGE>

                                    EXHIBIT A

                      DEPICTION OF THE EXPANSION PREMISES

                               AND MECHANICAL ROOM

                                       5

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                                  [FLOOR PLAN]

<PAGE>

                                    EXHIBIT B

                                   WORK LETTER

         THIS WORK LETTER dated as of November 15, 2000 (this "WORK LETTER") is
made and entered into by and between ARE- 100 PHILIPS PARKWAY, LLC, a Delaware
limited liability company ("LANDLORD"), and MEMORY PHARMACEUTICALS CORP., a
Delaware corporation ("TENANT"), and is attached to and made a part of the
Second Amendment to Lease dated November 15, 2000 (the "SECOND AMENDMENT"), by
and between Landlord and Tenant. Any initially capitalized terms used but not
defined herein shall have the meanings given them in the Second Amendment.

         1.       General Requirements

                  (a)      Tenant's Authorized Representative. Tenant designates
         Joanne Leonard ("TENANT'S REPRESENTATIVE") as the only person
         authorized to act for Tenant pursuant to this Work Letter. Landlord
         shall not be obligated to respond to or act upon any request, approval,
         inquiry or other communication ("COMMUNICATION") from or on behalf of
         Tenant in connection with this Work Letter unless such Communication is
         in writing from Tenant's Representative. Tenant may change Tenant's
         Representatives at any time upon not less than 5 Business Days advance
         written notice to Landlord. No period set forth herein for any approval
         of any matter by Tenant's Representative shall be extended by reason of
         any change in Tenant's Representative.

                  (b)      Landlord's Authorized Representative. Landlord
         designates Vincent Ciruzzi and Oliver Sherrill ("LANDLORD'S
         REPRESENTATIVE") as the only persons authorized to act for Landlord
         pursuant to this Work Letter. Tenant shall not be obligated to respond
         to or act upon any request, approval, inquiry or other Communication
         from or on behalf of Landlord in connection with this Work Letter
         unless such Communication is in writing from Landlord's Representative.
         Landlord may change Landlord's Representatives at any time upon not
         less than 5 Business Days advance written notice to Tenant. No period
         set forth herein for any approval of any matter by Landlord's
         Representative shall be extended by reason of any change in Landlord's
         Representative.

                  (c)      Architects, Consultants and Contractors. The
         architect ("ARCHITECT"), engineering consultants, design team, general
         contractor ("CONTRACTOR") and all subcontractors' responsible for
         construction of Tenant's Work, as defined below, shall be selected by
         Tenant, and approved by Landlord in Landlord's reasonable discretion.

         2.       Tenant Improvements

                  (a)      Tenant Improvements Defined. As used herein, "TENANT
         IMPROVEMENTS" shall mean all improvements to the Expansion Space
         desired by Tenant of a fixed and permanent nature. Other than providing
         the TI Allowance hereunder, Landlord shall not have any obligation
         whatsoever with respect to finishing the Premises for Tenant's use and
         occupancy. The construction of the Tenant Improvements is herein
         referred to as "TENANT'S WORK."

                  (b)      Tenant's Space Plans. Tenant may, until June 30,
         2003, prepare and submit for Landlord's review and approval schematic
         drawings and outline specifications (the "DESIGN DRAWINGS") detailing
         Tenant's requirements for the Tenant Improvements, which Tenant
         Improvements shall be consistent with the Permitted Use. Not more than
         10 Business Days after each such submission, Landlord shall deliver to
         Tenant Landlord's reasonable written objections, questions or comments
         with regard to the Design Drawings so submitted. Tenant shall cause the
         Design Drawings to be revised to address such written comments and
         shall resubmit said drawings to Landlord for approval. Such process
         shall continue until Landlord

                                       6

<PAGE>

         has approved the Design Drawings. If any proposed work of improvement
         set forth on the Design Drawings or any logical development of the
         Design Drawings has an adverse impact on the structure or operational
         efficiency of the Building or portions of the Building lying outside
         the Premises, all costs of mitigating such adverse impacts shall be
         paid from the TI Fund.

                  (c)      Preliminary Plans. Following Landlord's approval of
         the Design Drawings, Tenant shall prepare and submit for Landlord's
         review and approval preliminary plans and specifications for Tenant's
         Work (the "PRELIMINARY PLANS"). Landlord shall have the right to
         approve or disapprove the Preliminary Plans, which approval shall not
         be unreasonably withheld or delayed, provided, however, that except for
         matters affecting the Structure, as defined below, and matters that do
         not comply with all applicable building and land use laws, rules and
         regulations, Landlord may not disapprove any matter that is consistent
         with the Design Drawings. "Structure" shall mean: (i) structural
         portions of the Building including exterior walls, roof, foundation or
         the core of the Building, (ii) the exterior of the Building, or (iii)
         any of the Building systems, including, without limitation, elevator,
         plumbing, air conditioning, heating electrical, security, life safety
         or power. Tenant shall cause the Preliminary Plans to be revised to
         address such written comments and shall resubmit said drawings to
         Landlord for approval. Such process shall continue until Landlord has
         approved the Preliminary Plans. If Landlord fails to give written
         notice of its approval or disapproval within 5 business days following
         its receipt of the Preliminary Plans or any required modification or
         amendment thereof, the same shall be deemed to have been approved by
         Landlord. Tenant shall be solely responsible for ensuring that the
         Preliminary Plans reflect Tenant's requirements for Tenant's Work.

                  (d)      Final Plans and Specifications.

                           (i)      Following Landlord's approval of the
                  Preliminary Plans, Tenant shall cause the Architect to prepare
                  and deliver to Landlord for review: (i) construction plans,
                  specifications and drawings for Tenant's Work ("CONSTRUCTION
                  DRAWINGS"), and (ii) a detailed cost estimate for Tenant's
                  Work broken down by trade (i.e., mechanical, electrical,
                  plumbing, etc.), unit prices for the items specified in the
                  Construction Drawings and a project construction schedule in a
                  format reasonably acceptable to both parties (collectively
                  such items listed in clauses (i) and (ii) are referred to
                  herein as the "CONSTRUCTION DATA"). Landlord shall have the
                  right to approve or disapprove the Construction Drawings,
                  which approval shall not be unreasonably withheld or delayed.
                  Landlord may participate in all design meetings with Tenant,
                  the Architect, Contractor and other design professional as
                  appropriate in the course of the development of the
                  Construction Data. Landlord shall deliver its approval or
                  disapproval of the Construction Drawings to Tenant not later
                  than 5 business days after Landlord's receipt of same. If
                  Landlord disapproves the Construction Drawings such
                  disapproval shall be accompanied by detailed written comments
                  setting forth the basis for such disapproval. Tenant and the
                  Architect shall, within 5 business days after receipt of
                  Landlord's disapproval of the Construction Drawings cause the
                  Construction Drawings to be redrafted to address such issues,
                  and shall resubmit them for Landlord's approval as described
                  herein until Landlord approves the Construction Drawings.
                  Tenant shall be solely responsible for ensuring that the
                  Construction Drawings reflect Tenant's requirements for the
                  Tenant Improvements.

                           (ii)     Landlord shall have the right to disapprove
                  the Construction Drawings which: (i) do not comply with all
                  applicable building and land use laws, rules and regulations,
                  (ii) in Landlord's reasonable opinion, adversely impact the
                  Structure or (iii) are not consistent with the Preliminary
                  Plans.

                                       7

<PAGE>


                           (iii)    No Tenant's Work may begin until final cost
                  estimates for such Tenant's Work have been received and
                  reasonably approved by Landlord.

         3.       Performance of Tenant's Work.

                  (a)      Commencement and Permitting of Tenant's Work. Tenant
         shall commence construction of Tenant's Work upon obtaining all
         applicable governmental approvals and a building permit authorizing the
         construction of Tenant's Work (collectively, the "BUILDING PERMITS"),
         which Building Permits shall be paid for out of the TI Fund (as defined
         in Section 5.4 below), and shall diligently prosecute such construction
         to Substantial Completion. Landlord shall assist Tenant in obtaining
         the Building Permits.

                  (b)      Completion of Tenant's Work. Tenant shall
         substantially complete or cause to be substantially completed Tenant's
         Work in a good and workmanlike manner, in accordance with the Building
         Permits, subject to Minor Variations and normal "PUNCH LIST" items of a
         non-material nature which do not interfere with the use of the Premises
         ("SUBSTANTIAL COMPLETION"). Upon the Substantial Completion of Tenant's
         Work, Tenant shall require the Architect and the general contractor to
         execute and deliver, for the benefit of Tenant and Landlord, a
         Certificate of Substantial Completion in the form of the American
         Institute of Architects document G704. For purposes of this Work
         Letter, "MINOR VARIATIONS" shall mean any modifications reasonably
         required: (i) to comply with all applicable Legal Requirements and/or
         to obtain or to comply with any required permit (including the Building
         Permits); (ii) to comply with any request by the Tenant for
         modifications to Tenant's Work; (iii) to comport with good design,
         engineering and construction practices which are not material; or (iv)
         to make reasonable adjustments for field deviations or conditions
         encountered during the construction of Tenant's Work.

                  (c)      Construction Defects. Landlord shall have no
         obligation or liability of any kind to remedy or cause any responsible
         contractor to remedy: (i) any non-compliance of Tenant's Work with
         Code, (ii) any claim that Tenant's Work was not completed substantially
         in accordance with the Construction Drawings, or (iii) any other defect
         in Tenant's Work (collectively a "CONSTRUCTION DEFECT"), other than to
         cooperate, at no cost to Landlord with Tenant should Tenant elect to
         pursue a claim against any such contractor, provided that Tenant
         indemnifies and holds Landlord harmless from and against any liability,
         loss, cost damage or expense in connection with any such claim. Tenant
         shall be entitled to receive the benefit of all construction warranties
         and manufacturer's equipment warranties relating to equipment installed
         in the Premises.

         4.       Changes. If Tenant shall desire any change or series of
related changes to Tenant's Work the implementation of which is estimated to
change the Budget, as defined below by $25,000 or more (whether increasing or
decreasing the Budget) ("CHANGES"), Tenant shall notify Landlord in writing in
substantially the same form as the AIA standard change order form (a "CHANGE
REQUEST"), which Change Request shall detail the nature and extent of any such
Change. Such Change Request must be signed by Tenant's Representative. Landlord
shall approve or disapprove such Change Request within 5 Business Days of
receipt of such Change Request; provided, however that Landlord shall only
disapprove Change Requests which: (i) do not comply with all applicable building
and land use laws, rules and regulations, or (ii) in Landlord's reasonable
opinion, adversely impact the Structure. Before proceeding with any such Change
approved by Landlord, Tenant shall submit to Landlord in writing, within 10
Business Days of receipt of Landlord's approval of the Change Request (or such
longer period of time as is reasonably required depending on the extent of the
Change Request), an analysis of the additional cost or savings involved,
including, without limitation construction, material, architectural and
engineering costs and shall deposit with landlord, if applicable, any additional
Excess Costs resulting from such Change.

                                       8

<PAGE>

         5.       Costs.

                  (a)      Budget For Tenant Improvements. Before the
         commencement of construction of Tenant's Work, Landlord shall be
         provided a detailed breakdown, by trade, of the costs incurred or which
         will be incurred, in connection with the design and construction of the
         Tenant's Work (the "BUDGET"). The Budget shall be based upon the
         Construction Drawings approved by Landlord and shall include a payment
         to Landlord, of administrative rent equal ("ADMINISTRATIVE RENT") to 3%
         of the Budget (but not to exceed $50,000) for monitoring and inspecting
         the construction of Tenant's Work including but not limited to the
         review of a drawings, plans specifications, permits, budgets, change
         requests and other such Tenant required submittal relating to this Work
         Letter, which sum shall be payable from the TI Fund. Such
         Administrative Rent shall include, without limitation, all
         out-of-pocket costs, expenses and fees incurred by or on behalf of
         Landlord arising from, out of, or in connection with, such monitoring
         of the construction of the Tenant's Work, and shall be payable out of
         the TI Fund. If the Budget is greater than the TI Fund (as defined
         below), Tenant shall deposit with Landlord the difference, in cash,
         prior to the commencement of construction of the Tenant Improvements,
         for disbursement by Landlord as described in Section 5(e).

                  (b).     TI Allowance. Landlord shall provide to Tenant a
         tenant improvement TI Allowance ("TI ALLOWANCE") in the amount of $150
         per rentable square foot of the Expansion Space not to exceed an
         aggregate Tenant Improvement Allowance of $3,000,000. Before commencing
         any Tenant's Work, Tenant shall notify Landlord how much TI Allowance
         Tenant has elected to receive from Landlord. Such election shall be
         final and binding on Tenant, and may not thereafter be modified without
         Landlord's consent, which may granted or withheld in Landlord's sole
         and absolute discretion. The TI Allowance shall be disbursed by
         Landlord in accordance with this Work Letter.


                  (c)      Costs Includable in TI Fund. The TI Fund shall be
         used solely for the payment of design and construction costs in
         connection with the construction of the Tenant Improvements including,
         without limitation, Tenant's project management and regulatory
         consultants, the cost of preparing the Design Drawings, the Preliminary
         Plans and the Construction Drawings, all costs set forth in the Budget,
         including Landlord's Administrative Rent and the cost of Changes
         (collectively, "COSTS"). Notwithstanding anything to the contrary
         contained herein, the TI Fund shall not be used to purchase any
         furniture, personal property or other non-building system materials or
         equipment, including, but not be limited to, biological safety cabinets
         and other scientific equipment not incorporated into the Improvements;
         provided, however that Tenant may, at such time as Tenant may elect,
         use up to $20,000 of the TI Allowance in the aggregate for the purpose
         of installing conduit and wire (and/or reusing existing conduit and
         wire) from the Project central mechanical/electrical room to the
         demising wall of the Expansion Space. Landlord shall use reasonable
         efforts to notify Tenant 30 days before commencement of construction of
         tenant improvements for any third party in any portion of the remaining
         space.

                  (d)      Excess Costs. It is understood and agreed that
         Landlord is under no obligation to bear any portion of the cost of any
         of the Tenant Improvements except to the extent of the TI Allowance. If
         at any time and from time-to-time, the remaining Costs under the Budget
         exceed the remaining unexpended TI Fund ("EXCESS COSTS"), Tenant shall
         pay 100% of all such Excess Costs until the remaining Costs under the
         Budget are equal to or less than the remaining unexpended TI Allowance,
         as a condition precedent to Landlord's funding the cost of any further
         Tenant's Work. If Tenant fails to make any payment of Costs, or is late
         in paying such Costs such that Landlord cures such default, Landlord
         shall have all of the rights and remedies set forth in the Lease for a
         Default thereunder (including, but not limited to, the right to
         interest at the Default Rate on amounts so advanced), and for purposes
         of any litigation instituted with regard to such amounts the same will
         be considered Rent. Such Excess Costs together with the TI Allowance
         are herein referred to as the "TI FUND." Notwithstanding

                                       9

<PAGE>

         anything to the contrary set forth in this Section, Tenant shall be
         fully and solely liable for any costs of Tenant's Work in excess of the
         TI Allowance.

                  (e)      Payment for Tenant's Work. Not more than once a month
         during the performance of any of Tenant's Work, upon submission of a
         disbursement request in the form of Landlord's standard draw package,
         which shall include American Institute of Architects document G702 and
         G703, an Architect's certificate as to the work done, a notarized
         certification from the Contractor, and such invoices and lien waivers
         as Landlord shall require (the "DRAW PACKAGE"), all in form and
         substance as Landlord shall reasonably require, Landlord shall make
         disbursements to pay the then due costs of Tenant's Work as shown in
         the approved Draw Package within 10 business days of receipt of the
         complete Draw Package. Landlord shall have no obligation to make any
         disbursements of the Tenant Improvement Allowance after December 31,
         2003. Upon making any such disbursement of the Tenant Improvement
         Allowance, Base Rent for the Expansion Space shall be adjusted as
         provided in Section 7 of the Second Amendment.

         6.       Miscellaneous

                  (a)      Consents. Whenever consent or approval of either
         party is required under this Work Letter, that party shall not
         unreasonably withhold, condition or delay such consent or approval,
         except as may be expressly set forth herein to the contrary.

                  (b)      Modification. No modification, waiver or amendment of
         this Work Agreement or of any of its conditions or provisions shall be
         binding upon Landlord or Tenant unless in writinq signed by Landlord
         and Tenant.

                  (c)      Counterparts. This Work Letter may be executed in any
         number of counterparts but all counterparts taken together shall
         constitute a single document.

                  (d)      Governing Law. This Work Letter shall be governed by,
         construed and enforced in accordance with the internal laws of the
         state in which the Premises are located, without regard to choice of
         law principles of such State.

                  (e)      Time of the Essence. Time is of the essence of this
         Work Agreement and of each and all provisions thereof.

                  (f)      Default. Notwithstanding anything set forth herein or
         in the Lease to the contrary, Landlord shall not have any obligation to
         perform any work hereunder or to fund any portion of the TI Fund during
         any period Tenant is in Default under the Lease.

                  (g)      Severability. If any term or provision of this Work
         Letter is declared invalid or unenforceable, the remainder of this
         Work Letter shall not be affected by such determination and shall
         continue to be valid and enforceable.

                  (h)      Merger. All understanding and agreements, oral or
         written, heretofore made between the parties hereto and relating to
         Landlord's Work are merged in this Work Letter which alone (but
         inclusive of provisions of the Lease incorporated herein and the final
         approved constructions drawings and specifications prepared pursuant
         hereto) fully and completely expresses the agreement between Landlord
         and Tenant with regard to the matters set forth in this Work Letter.

                  (i)      Entire Agreement. This Work Letter is made as a part
         of and pursuant to the Lease and, together with the Lease, constitutes
         the entire agreement of the parties with respect to the subject matter
         hereof. This Work Letter is subject to all of the terms and

                                       10

<PAGE>

         imitation set forth in the Lease, and neither party shall have any
         rights or remedies under this Work Letter separate and apart from their
         respective remedies pursuant to the Lease.

         IN WITNESS WHEREOF, Landlord and Tenant have executed this Work Letter
to be effective on the date first above written.

                               TENANT:

                               MEMORY PHARMACEUTICALS CORP.,
                               a Delaware corporation

                               By: /s/ Joanne Leonard
                                  --------------------
                               Its: Sr VP, CFO

                               LANDLORD:

                               ARE - 100 PHILLIPS PARKWAY, LLC,
                               a Delaware limited liability company

                               By: ALEXANDRIA REAL ESTATE EQUITIES, L.P., a
                                   Delaware limited partnership, managing member

                                   By:  ARE-QRS CORP.,
                                        a Maryland corporation,
                                        general partner

                                        By:  /s/ Michael C. Keley
                                             -------------------------
                                        Its: Michael C. Keley
                                             Senior Vice President
                                             Real Estate Legal Affairs

                                       11